The , sometimes shortened to the Inland Sea, is the body of water separating
Honshū
, historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island ...
,
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
, and
Kyūshū, three of the four main islands of
Japan. It serves as a
waterway
A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. A first distinction is necessary ...
connecting the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...
to the
Sea of Japan
The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...
. It connects to
Osaka Bay
Osaka Bay (大阪湾 ''Ōsaka-wan'' ) is a bay in western Japan. As an eastern part of the Seto Inland Sea, it is separated from the Pacific Ocean by the Kii Channel and from the neighbor western part of the Inland Sea by the Akashi Strait ...
and provides a sea transport link to industrial centers in the
Kansai
The or the , lies in the southern-central region of Japan's main island Honshū. The region includes the prefectures of Nara, Wakayama, Kyoto, Osaka, Hyōgo and Shiga, often also Mie, sometimes Fukui, Tokushima and Tottori. The metropolitan ...
region, including
Osaka
is a designated city in the Kansai region of Honshu in Japan. It is the capital of and most populous city in Osaka Prefecture, and the third most populous city in Japan, following Special wards of Tokyo and Yokohama. With a population of ...
and
Kobe
Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, w ...
. Before the construction of the
San'yō Main Line
The is a major railway line owned by JR Group companies in western Japan, connecting Kōbe Station and Moji Station, largely paralleling the coast of the Inland Sea, in other words, the southern coast of western Honshu. The San'yō Shinkansen ...
, it was the main transportation link between Kansai and Kyūshū.
Yamaguchi,
Hiroshima,
Okayama
is the capital city of Okayama Prefecture in the Chūgoku region of Japan. The city was founded on June 1, 1889. , the city has an estimated population of 720,841 and a population density of 910 persons per km2. The total area is .
The city is ...
,
Hyōgo,
Osaka
is a designated city in the Kansai region of Honshu in Japan. It is the capital of and most populous city in Osaka Prefecture, and the third most populous city in Japan, following Special wards of Tokyo and Yokohama. With a population of ...
,
Wakayama Wakayama may refer to:
*Wakayama Prefecture, a prefecture of Japan
*Wakayama (city), the capital city of Wakayama Prefecture, Japan
*Wakayama Station, a train station in Wakayama, Wakayama
*Wakayama University
, or , is a national university loc ...
,
Kagawa,
Ehime
is a prefecture of Japan located on the island of Shikoku. Ehime Prefecture has a population of 1,342,011 (1 June 2019) and has a geographic area of 5,676 km2 (2,191 sq mi). Ehime Prefecture borders Kagawa Prefecture to the northeast, Tokus ...
,
Tokushima
is a prefecture of Japan located on the island of Shikoku. Tokushima Prefecture has a population of 728,633 (1 October 2019) and has a geographic area of 4,146 km2 (1,601 sq mi). Tokushima Prefecture borders Kagawa Prefecture to the north, ...
,
Fukuoka
is the List of Japanese cities by population, sixth-largest city in Japan, the second-largest port city after Yokohama, and the capital city of Fukuoka Prefecture, Japan. The city is built along the shores of Hakata Bay, and has been a center ...
, and
Ōita prefectures have coastlines on the Seto Inland Sea; the cities of
Hiroshima,
Iwakuni
is a city located in Yamaguchi Prefecture, Japan.
History
Iwakuni was formerly the castle town of the Iwakuni han, which was formed by Lord Hiroie Kikkawa after he was banished there for supporting the defeated shōgun. The Kikkawa clan rule ...
,
Takamatsu
270px, Takamatsu City Hall
270px, Aerial view of Takamatsu city center
270px, View from Yashima to Takashima port
is a city located in Kagawa Prefecture, Japan. , the city had an estimated population of 414,134 in 190120 households and a popul ...
, and
Matsuyama
270px, Matsuyama City Hall
270px, Ehime Prefectural Capital Building
is the capital city of Ehime Prefecture on the island of Shikoku in Japan and also Shikoku's largest city. , the city had an estimated population of 505,948 in 243541 househ ...
are also located on it.
The
Setouchi region encompasses the sea and surrounding coastal areas. The region is known for its moderate climate, with a stable year-round temperature and relatively low rainfall levels. The sea is famous for its periodic caused by dense groupings of certain
phytoplankton
Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'.
P ...
that result in the death of large numbers of fish. Since the 1980s, the sea's northern and southern shores have been connected by the three routes of the
Honshū–Shikoku Bridge Project
The is a system of bridges connecting the islands of Honshu and Shikoku across the Inland Sea of Japan, which were previously only connected by ferry. It consists of three major connections. All bridges are now controlled by the Honshu-Shikok ...
, including the
Great Seto Bridge
The is a series of double deck bridges connecting Okayama and Kagawa prefectures in Japan across a series of five small islands in the Seto Inland Sea. Built over the period 1978–88, it is one of the three routes of the Honshū–Shikoku Bri ...
, which serves both railroad and automobile traffic.
Extent
The
International Hydrographic Organization
The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. , the IHO comprised 98 Member States.
A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters ...
's definition of the limits of the Seto Inland Sea (published in 1953) is as follows:
''On the West.'' The southeastern limit of the Japan Sea Shimonoseki-kaikyo. A line running from Nagoya Saki (130°49'E) in Kyûsû through the islands of Uma Sima and Muture Simia (33°58',5N) to Murasaki Hana (34°01'N) in Honsyû">Kyushu">Kyûsû through the islands of Uma Sima and Muture Simia (33°58',5N) to Murasaki Hana (34°01'N) in Honsyû/nowiki>.
''On the East (Kii Suidô).'' A line running from Takura Saki (34°16'N) in Honsyû to Oishi Hana in the island of
Awazi, through this island to Sio Saki (34°11'N) and on to Oiso Saki in Shikoku">Sikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ' ...
.
''On the South ( Bungo Suidô).'' A line joining Sada Misaki (33°20'N) in Sikoku and Seki Saki in Kyûsyû.
The range of the Seto Inland Sea by the Territorial Sea Law (:ja:領海及び接続水域に関する法律">領海及び接続水域に関する法律) is . The range of the Seto Inland Sea according to the Setouchi Law and the Setouchi Law Enforcement Order is .
Geographical features

The Seto Inland Sea is 450 km (280 mi) long from east to west. The width from south to north varies from 15 to 55 km (10 to 34 mi). In most places, the water is relatively shallow. The average depth is 38 m (125 ft); the greatest depth is 105 m (344 ft).
Hydrologically, Seto Inland Sea is not a true
inland sea
An inland sea (also known as an epeiric sea or an epicontinental sea) is a continental body of water which is very large and is either completely surrounded by dry land or connected to an ocean by a river, strait, or "arm of the sea". An inland s ...
, being neither an
epeiric
An inland sea (also known as an epeiric sea or an epicontinental sea) is a continental body of water which is very large and is either completely surrounded by dry land or connected to an ocean by a river, strait, or "arm of the sea". An inland s ...
body of water like
Hudson Bay
Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...
nor an isolated
endorheic basin
An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into la ...
like the
Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the List of lakes by area, world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad s ...
. Rather, it is actually a
marginal sea
This is a list of seas of the World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and straits.
Terminology
* Ocean – the four to seven largest named bodies of water in the World Ocean, all of which have "Oce ...
; a division of a wider ocean (in this case the Pacific) which is partially enclosed by islands, archipelagos, or peninsulas, (here, the Japanese Home Islands) adjacent to or widely open to the open ocean at the surface. The
Naruto Strait
is a strait between Awaji Island and Shikoku in Japan. It connects Harima Nada, the eastern part of the Inland Sea and the Kii Channel. A famous feature of the strait is the Naruto whirlpools. Ōnaruto Bridge
The is a suspension bridge ...
connects the eastern part of the Seto Inland Sea to the
Kii Channel
The , also called the Kii Strait, is a strait separating the Japanese island of Shikoku from the Kii Peninsula on the main island of Honshū. This strait connects the Inland Sea with the Pacific Ocean.
The name of the strait derives from Kii P ...
, which in turn connects to the Pacific. The western part of the Seto Inland Sea connects to the Sea of Japan through the
Kanmon Straits
The or the Straits of Shimonoseki is the stretch of water separating Honshu and Kyushu, two of Japan's four main islands. On the Honshu side of the strait is Shimonoseki (, which contributed "Kan" () to the name of the strait) and on the Kyushu ...
and to the Pacific through the
Bungo Channel
The is a strait separating the Japanese islands of Kyushu and Shikoku. It connects the Pacific Ocean and the Seto Inland Sea on the western end of Shikoku. The narrowest part of this channel is the Hōyo Strait.
In the English-speaking world, ...
.
Each part of the Seto Inland Sea has a separate name in Japanese. For example, refers to the strait between Ehime, Yamaguchi, and Ōita prefectures in the western portion of the sea; is the open expanse west of the
Geiyo Islands
The are a group of islands in the Seto Inland Sea, under the administration of Hiroshima Prefecture and Ehime Prefecture. Some of the largest islands in archipelago are connected by the Nishiseto Expressway bridge system connecting Honshu and Shi ...
, near Hiroshima prefecture; and refers to the expanse between Yamaguchi prefecture and
Suō-Ōshima. There are also many straits located between the major islands, as well as a number of smaller ones that pass between islands or connect the Seto Inland Sea to other seas or the Pacific. Almost 3,000 islands are located in the Seto Inland Sea. The largest island is
Awaji-shima, and the second largest is
Shōdo-shima. Many of the smaller islands are uninhabited.
Major islands
*Eastern part:
Awaji Island,
Shōdo Island, Ieshima Islands,
Naoshima
is an island in Japan's Seto Inland Sea, part of Kagawa Prefecture. The island is best known for its many contemporary art installations and museums. The administers Naoshima and 26 smaller islands nearby. As of 2020, the town has an estimated ...
Islands,
Shiwaku Islands
The or are an archipelago in the Seto Inland Sea, between the larger Japanese islands of Honshu and Shikoku.
The group is situated between Okayama Prefecture and Kagawa Prefecture in the western Bisan Seto and consists of 28 islands of variou ...
,
Yumeshima
is an artificial island. It is part of Konohana-ku (此花区), one of the 24 wards of Osaka, Japan. It is near the mouth of the Yodo River. When all the landfill is completed the total area will be .
It will be the site of Expo 2025, a Wor ...
*Central part:
Ōmishima,
Innoshima
is an island and former city in Hiroshima Prefecture, Japan. The island is located within the Geiyo Islands of the Seto Inland Sea. The city was founded on May 1, 1953.
, the city had an estimated population of 27,465 and a population density o ...
,
Itsukushima
is an island in the western part of the Inland Sea of Japan, located in the northwest of Hiroshima Bay. It is popularly known as , which in Japanese means "Shrine Island". The island is one of Hayashi Gahō's Three Views of Japan specified i ...
(popularly known as Miyajima),
Hinase Islands,
Kasaoka Islands
The are a group of 31 islands in the Seto Inland Sea of Okayama Prefecture. They are part of the city of Kasaoka.
The seven inhabited islands in the group are:
* Takashima Island 高島 (岡山県笠岡市)
* Shiraishi Island, 白石島
* Kita ...
*Western part:
Suō-Ōshima,
Uwakai Islands
The is a limited express
A limited express is a type of express train service. It refers to an express service that stops at a limited number of stops in comparison to other express services on the same or similar routes.
Japan
The term "l ...
,
Hashira-jima Islands.
Fauna
Over 500 marine species are known to live in the Seto Inland Sea. Examples are the
ayu
Ayu or AYU may refer to:
* Ayu (given name)
* Ayu sweetfish (''Plecoglossus altivelis''), a species of smelt
* ''Ayu'', a local name for the African manatee
* Ayu (singer) or Ayumi Hamasaki, Japanese singer
* Ayu Islands, a small archipelago in I ...
, an
amphidromous
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...
fish,
horseshoe crab
Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are Chelicerata, chelicerates, most closely rela ...
,
finless porpoise
''Neophocaena'' is a genus of porpoise native to the Indian and Pacific oceans, as well as the freshwater habitats of the Yangtze River basin in China. They are commonly known as finless porpoises. Genetic studies indicate that ''Neophocaena'' ...
, and
great white shark
The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocean ...
, which has occasionally attacked people in the Seto Inland Sea. In the past,
whale
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
s entered the sea to feed or breed, however because of
whaling
Whaling is the process of hunting of whales for their usable products such as meat and blubber, which can be turned into a type of oil that became increasingly important in the Industrial Revolution.
It was practiced as an organized industry ...
and pollution, they are rarely seen.
History
During the last
ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...
the
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardise ...
was lower than today. After the ice age, sea water poured into a basin between the
Chūgoku mountains and
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
mountains and formed the Seto Inland Sea as it is known today. From ancient times, the Seto Inland Sea served as a main transport line between its coastal areas, including what is today the Kansai region and Kyūshū. It was also a main transport line between Japan and other countries, including Korea and China. Even after the creation of major highways such as the
Nankaidō
is a Japanese geographical term. It means both an ancient division of the country and the main road running through it. The road connected provincial capitals in this region. It was part of the Gokishichidō system.
The ''Nankaidō'' encompass ...
and
San'yōdō
is a Japanese geographical term. It means both an ancient division of the country and the main road running through it. The San'yōdō corresponds for the most part with the modern conception of the San'yō region. This name derives from the id ...
, the Seto Inland Sea remained a major transport route. There are records that some foreign emissaries from China and Korea sailed on the Seto Inland Sea.
The importance of water traffic gave rise to private navies in the region. In many documents, these navies were called , or simply pirates. Sometimes they were considered to be public enemies, but in most cases they were granted the right to self-governance as a result of their strength. During the feudal period, ''suigun'' seized power in most coastal areas. The Kono in
Iyo Province
was a province of Japan in the area of northwestern Shikoku. Nussbaum, Louis-Frédéric. (2005). "''Tosa''" in . Iyo bordered on Sanuki Province to the northeast, Awa to the east, and Tosa to the south. Its abbreviated form name was . In te ...
(today
Ehime Prefecture
is a prefecture of Japan located on the island of Shikoku. Ehime Prefecture has a population of 1,342,011 (1 June 2019) and has a geographic area of 5,676 km2 (2,191 sq mi). Ehime Prefecture borders Kagawa Prefecture to the northeast, Toku ...
) and
Kobayakawa Kobayakawa (written: ) is a Japanese surname. Notable people with the surname include:
*, Japanese ''daimyō''
*, Japanese samurai
*, Japanese baseball player
*, Japanese samurai and ''daimyō''
Fictional characters
*, a character in the manga ser ...
(later
Mōri) in
Aki Province
or Geishū () was a province in the Chūgoku Region of western Honshū, comprising the western part of what is today Hiroshima Prefecture.
History
When Emperor Shōmu ordered two official temples for each province (one for male Buddhist pri ...
(today a part of
Hiroshima Prefecture
is a prefecture of Japan located in the Chūgoku region of Honshu. Hiroshima Prefecture has a population of 2,811,410 (1 June 2019) and has a geographic area of 8,479 km² (3,274 sq mi). Hiroshima Prefecture borders Okayama Prefecture to the ...
) clans were two of the more famous ''suigun'' lords. In the 12th century,
Taira no Kiyomori
was a military leader and ''kugyō'' of the late Heian period of Japan. He established the first samurai-dominated administrative government in the history of Japan.
Early life
Kiyomori was born in Heian-kyō, Japan, in 1118 as the first s ...
planned to move the capital from
Kyoto
Kyoto (; Japanese: , ''Kyōto'' ), officially , is the capital city of Kyoto Prefecture in Japan. Located in the Kansai region on the island of Honshu, Kyoto forms a part of the Keihanshin metropolitan area along with Osaka and Kobe. , the ...
to the coastal village of Fukuhara (today
Kobe
Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, w ...
) to promote trade between Japan and the
Song dynasty
The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the res ...
of China. This transfer was unsuccessful, and soon after Kyoto became the capital again. Later, the
Battle of Yashima
Battle of Yashima (屋島の戦い) was one of the battles of the Genpei War on March 22, 1185 in the Heian period. It occurred in Sanuki Province (Shikoku) which is now Takamatsu, Kagawa.
Background
Following a long string of defeats, the T ...
took place off the coast of present-day Takamatsu.
In the
Edo period
The or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional ''daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was character ...
, the Seto Inland Sea was one of the busiest transport lines in Japan. It was a part of a navigational route around Japan's islands via the Sea of Japan. Many ships navigated from its coastal areas to the area along the Sea of Japan. Major ports in the Edo period were Osaka, Sakai, Shimotsui,
Ushimado, and Tomonoura. The Seto Inland Sea also served many ''
daimyō
were powerful Japanese magnates, feudal lords who, from the 10th century to the early Meiji period in the middle 19th century, ruled most of Japan from their vast, hereditary land holdings. They were subordinate to the shogun and nominall ...
s'' in the western area of Japan as their route to and from
Edo
Edo ( ja, , , "bay-entrance" or "estuary"), also romanized as Jedo, Yedo or Yeddo, is the former name of Tokyo.
Edo, formerly a ''jōkamachi'' (castle town) centered on Edo Castle located in Musashi Province, became the ''de facto'' capital of ...
, to fulfill their obligations under ''
sankin-kōtai
''Sankin-kōtai'' ( ja, 参覲交代/参覲交替, now commonly written as ja, 参勤交代/参勤交替, lit=alternate attendance, label=none) was a policy of the Tokugawa shogunate during most of the Edo period of Japanese history.Jansen, M ...
''. Many used ships from Osaka. Thanks to transport through the Seto Inland Sea, Osaka became the economic center of Japan. Each
''han'' had an office called ''Ozakayashiki'' in Osaka. These ''Ozakayashiki'' were among Japan's earliest forms of banks, facilitating domestic trade and helping to organize the income of the ''daimyo'', which was in the form of ''
koku'', giant bales of rice.
The Seto Inland Sea was also part of the official Chosendentsushi route, bringing Korean emissaries to the shogunate. After the
Meiji Restoration
The , referred to at the time as the , and also known as the Meiji Renovation, Revolution, Regeneration, Reform, or Renewal, was a political event that restored practical imperial rule to Japan in 1868 under Emperor Meiji. Although there were r ...
, the coastal cities along the Seto Inland Sea were rapidly industrialized. One of the headquarters of the
Japanese Navy
, abbreviated , also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy (IJN ...
was built in the town of
Kure
is a port and major shipbuilding city situated on the Seto Inland Sea in Hiroshima Prefecture, Japan. With a strong industrial and naval heritage, Kure hosts the second-oldest naval dockyard in Japan and remains an important base for the Japan ...
. Since the Meiji period, development of land transport has been reducing the importance of the Seto Inland Sea as a transport line. Remarkable land transportation innovations include the
San'yō Main Railroad Line in Honshū and the
Yosan Main Railroad Line in Shikoku (both completed before
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
) and three series of bridges connecting Honshū and Shikoku (completed in the late 20th century). The Seto Inland Sea is still used, however, by an international cargo transport line and several local transport lines connecting Honshū with Shikoku and Kyūshū.
Industry
Major cities with heavy industrial activity on the coast of the Seto Inland Sea include Osaka, Kobe, and Hiroshima. Smaller scale manufacturing and industry can also be found in
Kurashiki
is a historic Cities of Japan, city located in western Okayama Prefecture, Japan, sitting on the Takahashi River, on the coast of the Seto Inland Sea, Inland Sea. As of March 31, 2017, the city has an estimated population of 483,576 and a populat ...
,
Kure
is a port and major shipbuilding city situated on the Seto Inland Sea in Hiroshima Prefecture, Japan. With a strong industrial and naval heritage, Kure hosts the second-oldest naval dockyard in Japan and remains an important base for the Japan ...
,
Fukuyama, and
Ube
UBE or Ube may refer to:
* Ubiquitin-activating enzyme
* Ube, Yamaguchi, a city in Japan
* Uniform Bar Examination
* Unilateral Biportal Endoscopy
* Ube Industries, chemical company
* Union bound estimate, a probability theory bound
* Union of ...
in Honshū, and
Sakaide
270px, Sakaide City Hall
270px, Aerial view of Sakaide city center
is a city located in Kagawa Prefecture, Japan. , the city had an estimated population of 49,439 in 21347 households and a population density of and a population density of 530 p ...
,
Imabari
270px, Imabari City Hall
270px, Aerial view of Imabari city center
is a city in Ehime Prefecture, Japan. It is the second largest city in Ehime Prefecture. , the city had an estimated population of 152,111 in 75947 households and a population ...
, and
Niihama
270px, Niihama City Hall
270px, Aerial View of Central Niihama
is a city located in the eastern part of Ehime Prefecture, Japan. , the city had an estimated population of 115,824 in 57781 households and a population density of 490 persons per ...
in Shikoku. Major industries include
steel production, vehicle manufacture, ship building, textiles, and since the 1960s, oil refining and chemical products.
Imabari Shipbuilding
is a major Japanese ship building, marine engineering, and service company headquartered in Imabari, Ehime Prefecture, Japan.
It is Japan’s largest shipbuilder both in terms of tonnage and sales revenue, with design, research, construct ...
, Japan's largest ship building company, has its headquarters and some of its yards in
Imabari, Ehime
270px, Imabari City Hall
270px, Aerial view of Imabari city center
is a city in Ehime Prefecture, Japan. It is the second largest city in Ehime Prefecture. , the city had an estimated population of 152,111 in 75947 households and a population ...
Prefecture. Thanks to the moderate climate and beautiful landscape, fishing, agriculture, and tourism bring a lot of income to the area as well.
Transport

Today the Seto Inland Sea serves its coastal areas mainly for two purposes: first, international or domestic cargo transportation, and second, local transportation between coastal areas and islands on the sea. Major ports are Kobe, Okayama,
Takamatsu
270px, Takamatsu City Hall
270px, Aerial view of Takamatsu city center
270px, View from Yashima to Takashima port
is a city located in Kagawa Prefecture, Japan. , the city had an estimated population of 414,134 in 190120 households and a popul ...
, Tokushima, Matsuyama, and Hiroshima.
Historically, the Seto Inland Sea as transport line served four coastal areas: Kansai, Chūgoku, Shikoku, and eastern Kyūshū. The Seto Inland Sea provided each of these regions with local transportation and connected each region to the others and far areas, including the coastal area of the Sea of Japan, Korea, and China. After Kobe port was founded in 1868 to serve foreign ships, the Seto Inland Sea became a major international waterway with connection to the Pacific.
Development of land transportation shifted the travel between east and west — that is, between Honshū and Kyūshū — to railroad and road transport. Two coastal railways, San'yō Main Line in Honshū and Yosan Main Line, were built. Those railway lines stimulated the local economy and once invoked a rail mania. Many short railroads were planned to connect a certain station of those two lines and a local seaport on the Seto Inland Sea, and some of them were actually built. The Ministry of Railroads, later the
Japanese National Railways
The abbreviated JNR or , was the business entity that operated Japan's national railway network from 1949 to 1987.
Network Railways
As of June 1, 1949, the date of establishment of JNR, it operated of narrow gauge () railways in all 46 pref ...
and then
Shikoku Railway Company
The , commonly known as , is the smallest of the seven constituent companies of the Japan Railways Group (JR Group). It operates of intercity and local rail services in the four prefectures on the island of Shikoku in Japan. The company has it ...
, ran some train ferry lines between Honshū and Shikoku including the line between Uno Station (Tamano) and
Takamatsu Station (Takamatsu). When the
Great Seto Bridge
The is a series of double deck bridges connecting Okayama and Kagawa prefectures in Japan across a series of five small islands in the Seto Inland Sea. Built over the period 1978–88, it is one of the three routes of the Honshū–Shikoku Bri ...
was finished and began to serve the two coastal areas, that ferry line was abolished.
Highways & bridges

The main islands Honshū and Shikoku are connected by three series of bridges since the late 1980s. This improves land transportation between the connected islands. These series of bridges, collectively known as the
Honshū–Shikoku Bridge Project
The is a system of bridges connecting the islands of Honshu and Shikoku across the Inland Sea of Japan, which were previously only connected by ferry. It consists of three major connections. All bridges are now controlled by the Honshu-Shikok ...
, are, from east to west,
Akashi Kaikyō Bridge
The is a suspension bridge which links the city of Kobe on the Japanese island of Honshu to Iwaya on Awaji Island. It is part of the Kobe-Awaji-Naruto Expressway, and crosses the busy and turbulent Akashi Strait (''Akashi Kaikyō'' in Japan ...
,
Great Seto Bridge
The is a series of double deck bridges connecting Okayama and Kagawa prefectures in Japan across a series of five small islands in the Seto Inland Sea. Built over the period 1978–88, it is one of the three routes of the Honshū–Shikoku Bri ...
, and
Nishiseto Expressway
The , often called the is an expressway in Japan that connects Onomichi, Hiroshima and Imabari, Ehime, going through nine of the Geiyo Islands, including Ōshima, Ōmishima, and Innoshima. The road and multiple bridges crossing across the Se ...
.
Kobe-Awaji-Naruto Highway
The easternmost highway was built between 1976 and 1998. It leads from
Akashi Akashi may refer to:
People
* Akashi (surname)
Places
* Akashi, Hyōgo
* Akashi Station, a Japanese railroad station on the Sanyō Main Line
* Akashi Strait
* Akashi Kaikyō Bridge, crossing the former
* Akashi Castle
* Akashi Domain
* Akashi, th ...
(
Hyogo prefecture) on the
Akashi Kaikyō Bridge
The is a suspension bridge which links the city of Kobe on the Japanese island of Honshu to Iwaya on Awaji Island. It is part of the Kobe-Awaji-Naruto Expressway, and crosses the busy and turbulent Akashi Strait (''Akashi Kaikyō'' in Japan ...
(the longest
suspension bridge
A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridges, which lack vertical ...
in the world) to
Awaji Island, from there via the
Ōnaruto Bridge
The is a suspension bridge on the Kobe-Awaji-Naruto Expressway connecting Minamiawaji, Hyogo on Awaji Island with Naruto, Tokushima on Ōge Island, Japan. Completed in 1985, it has a main span of . Although it is one of the largest brid ...
to
Ōge-jima
is an island in the Seto Inland Sea administered under Naruto in Tokushima Prefecture.
Geography
Ōge-jima, also called Ōge Island, is located in the northeast of Tokushima Prefecture
is a prefecture of Japan located on the island of ...
(
Naruto
''Naruto'' is a Japanese manga series written and illustrated by Masashi Kishimoto. It tells the story of Naruto Uzumaki, a young ninja who seeks recognition from his peers and dreams of becoming the Hokage, the leader of his village. ...
,
Tokushima Prefecture
is a prefecture of Japan located on the island of Shikoku. Tokushima Prefecture has a population of 728,633 (1 October 2019) and has a geographic area of 4,146 km2 (1,601 sq mi). Tokushima Prefecture borders Kagawa Prefecture to the nort ...
) beyond the 1.3-kilometer wide
Naruto Strait
is a strait between Awaji Island and Shikoku in Japan. It connects Harima Nada, the eastern part of the Inland Sea and the Kii Channel. A famous feature of the strait is the Naruto whirlpools. Ōnaruto Bridge
The is a suspension bridge ...
and finally across the Muya Bridge to
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
.
Seto Chuo Highway
The Great Seto Bridge connects Okayama Prefecture with Kagawa Prefecture since 1988. It consists of a total of six two-storey bridges, whose lower floors are used by the railway (
Japan Railways Group
The Japan Railways Group, more commonly known as the or simply JR, consists of seven for-profit stock companies that took over most of the assets and operations of the government-owned Japanese National Railways (JNR) on April 1, 1987. Most ...
). The high speed
Shinkansen
The , colloquially known in English as the bullet train, is a network of high-speed railway lines in Japan. Initially, it was built to connect distant Japanese regions with Tokyo, the capital, to aid economic growth and development. Beyond ...
does not go to or on Shikoku.
Nishiseto Highway / Shimanami Highway
This is the first of three intersections of the Seto Inland Sea. Construction started in 1975, but was fully completed in 1999. It connects the Nishiseto-
Onomichi
is a city located in Hiroshima Prefecture, Japan, facing the Inland Sea. The city was founded on April 1, 1898. As of April 30, 2016, the city has an estimated population of 141,811 and a population density of 497.8 persons per km2. The total are ...
Highway in Hiroshima Prefecture with a total of ten bridges and several smaller islands with Imabari in
Ehime Prefecture
is a prefecture of Japan located on the island of Shikoku. Ehime Prefecture has a population of 1,342,011 (1 June 2019) and has a geographic area of 5,676 km2 (2,191 sq mi). Ehime Prefecture borders Kagawa Prefecture to the northeast, Toku ...
. Approximately 100,000 people live on those islands. The bridges are: Shin Onomichi Bridge,
Innoshima Bridge
The is a Japanese suspension bridge, part of the 59 kilometer Nishiseto Expressway
The , often called the is an expressway in Japan that connects Onomichi, Hiroshima and Imabari, Ehime, going through nine of the Geiyo Islands, including Ōs ...
, Ikuchi Bridge,
Tatara Bridge
The is a cable-stayed bridge that is part of the Nishiseto Expressway, commonly known as the Shimanami Kaidō しまなみ海道. The bridge has a center span of . As of 2010 it has the fourth longest main span of any cable-stayed bridge after ...
, Ōmishima Bridge, the two Ōshima bridges and the three Kurushima Kaikyo bridges. The
Kurushima-Kaikyō Bridge connects the island of
Ōshima to the main island of
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
.
Major tourist sites

The coastal area of the Seto Inland Sea is one of the most famous tourist destinations in Japan. Even before Japan opened to foreigners in the middle of the 19th century, the sea's beauty was praised and introduced to the Western world by those who visited Japan, including
Philipp Franz von Siebold
Philipp Franz Balthasar von Siebold (17 February 1796 – 18 October 1866) was a German physician, botanist and traveler. He achieved prominence by his studies of Japanese flora and fauna and the introduction of Western medicine in Japan. He was ...
, and after the country's opening,
Ferdinand von Richthofen
Baron Ferdinand Freiherr von Richthofen (5 May 18336 October 1905), better known in English as was a German traveller, geographer, and scientist. He is noted for coining the terms "Seidenstraße" and "Seidenstraßen" = " Silk Road(s)" or "Silk ...
and
Thomas Cook
Thomas Cook (22 November 1808 – 18 July 1892) was an English businessman. He is best known for founding the travel agency Thomas Cook & Son. He was also one of the initial developers of the " package tour" including travel, accommodati ...
.
Its coastal area, except for
Osaka Prefecture and a part of
Wakayama Prefecture
is a prefecture of Japan located in the Kansai region of Honshu. Wakayama Prefecture has a population of 944,320 () and has a geographic area of . Wakayama Prefecture borders Osaka Prefecture to the north, and Mie Prefecture and Nara Prefect ...
, was appointed the on March 16, 1934, as one of three oldest national parks in Japan.
Itsukushima Shrine
is a Shinto shrine on the island of Itsukushima (popularly known as Miyajima), best known for its "floating" ''torii'' gate. Nussbaum, Louis-Frédéric (2005)"''Itsukushima-jinja''"in ''Japan Encyclopedia'', p. 407. It is in the city of Hatsuk ...
, on the island of
Itsukushima
is an island in the western part of the Inland Sea of Japan, located in the northwest of Hiroshima Bay. It is popularly known as , which in Japanese means "Shrine Island". The island is one of Hayashi Gahō's Three Views of Japan specified i ...
in the city of
Hatsukaichi
is a city located in Hiroshima Prefecture, Japan. The name derives from a market traditionally held on the 20th of each month with ''hatsuka'' (廿日) meaning "20th day" and ''ichi'' (市) translating to "market". The market continues to this da ...
, is a
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. I ...
World Heritage Site
A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...
and one of the most famous Japanese sites outside
Tokyo
Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...
and
Kyoto
Kyoto (; Japanese: , ''Kyōto'' ), officially , is the capital city of Kyoto Prefecture in Japan. Located in the Kansai region on the island of Honshu, Kyoto forms a part of the Keihanshin metropolitan area along with Osaka and Kobe. , the ...
.
Shōdoshima
Shōdoshima or is an island located in the Inland Sea of Japan. The name means "Island of Small Beans". There are two towns on the island: Tonoshō and Shōdoshima, composing the district of Shōzu.
The island is famous as the setting for t ...
, nicknamed the "island of olives", and the
Naruto whirlpools
The are tidal whirlpools in the Naruto Strait, a channel between Naruto in Tokushima and Awaji Island in Hyōgo, Japan. The strait between Naruto and Awaji island has a width of about . The strait is one of the connections between the Paci ...
are two other well-known tourist sites. Neighboring locations like
Kotohira
is a town located in Nakatado District, Kagawa Prefecture, Japan. , the town had an estimated population of 8,105 in 3618 households and a population density of 960 persons per km². The total area of the town is . The town is best known as th ...
and
Okayama
is the capital city of Okayama Prefecture in the Chūgoku region of Japan. The city was founded on June 1, 1889. , the city has an estimated population of 720,841 and a population density of 910 persons per km2. The total area is .
The city is ...
are often combined with the tour of the Setouchi region. Some historic sites, including Yashima in
Takamatsu
270px, Takamatsu City Hall
270px, Aerial view of Takamatsu city center
270px, View from Yashima to Takashima port
is a city located in Kagawa Prefecture, Japan. , the city had an estimated population of 414,134 in 190120 households and a popul ...
and
Kurashiki
is a historic Cities of Japan, city located in western Okayama Prefecture, Japan, sitting on the Takahashi River, on the coast of the Seto Inland Sea, Inland Sea. As of March 31, 2017, the city has an estimated population of 483,576 and a populat ...
, also attract many visitors.
Hiroshima is the neighbor city to Itsukushima Shrine and another UNESCO World Heritage Site because of
atomic bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...
damage in 1945. Idol Unit
STU48
STU48 (Setouchi48) is a Japanese idol group and sister group of AKB48 named after the Setouchi Region. The group had a from 2019 to 2021. It is co-owned by the tourism board of Setouchi Region and is highly involved in their promotional efforts. ...
operate on a cruise on the Setuchi.
The eastern end of the Sea is now famous for the
Setouchi Triennale The Setouchi International Art Triennale is a contemporary art festival held every three years on several islands in the Seto Inland Sea
The , sometimes shortened to the Inland Sea, is the body of water separating Honshū, Shikoku, and Kyūshū ...
set up in 2010 with the next event happening in 2022. Some of this takes place on the island of
Naoshima
is an island in Japan's Seto Inland Sea, part of Kagawa Prefecture. The island is best known for its many contemporary art installations and museums. The administers Naoshima and 26 smaller islands nearby. As of 2020, the town has an estimated ...
, known colloquially as the art island, and the home of several permanent museums.
At the far eastern extremity, as the Sea meets the Pacific Ocean, are the
Naruto whirlpools
The are tidal whirlpools in the Naruto Strait, a channel between Naruto in Tokushima and Awaji Island in Hyōgo, Japan. The strait between Naruto and Awaji island has a width of about . The strait is one of the connections between the Paci ...
that can be reached by sight-seeing boats.
The
Shiwaku Islands
The or are an archipelago in the Seto Inland Sea, between the larger Japanese islands of Honshu and Shikoku.
The group is situated between Okayama Prefecture and Kagawa Prefecture in the western Bisan Seto and consists of 28 islands of variou ...
are a defined group numbering 28 that can be reached by ferry boat from
Marugame
is a city located in Kagawa Prefecture, Japan. , the city had an estimated population of 108,541 in 46101 households and a population density of 970 persons per km². The total area of the city is .
Geography
Marugame is located in north- ...
. Here
Richard Henry Brunton
Richard Henry Brunton FRGS MICE (26 December 1841 – 24 April 1901) was the so-called "Father of Japanese lighthouses". Brunton was born in Muchalls, Kincardineshire, Scotland. He was employed by the government of Meiji period Japan as a ...
built one of his lighthouses that can still be seen, and the grave of
Frank Toovey Lake
Frank Toovey Lake (1849–1868) died while serving in Japan with the British Royal Navy. After his death at the age of 19, he was interred on the island of Sanuki Hiroshima in the Seto Inland Sea. Since his burial – and until the present da ...
, a young midshipman in his survey party has become famous.
In the central area of Seto Inland Sea is
Mount Ishizuchi
is a mountain on the border of Saijō and Kumakōgen, in Ehime, Japan. This mountain is one of the 100 famous mountains in Japan. It is the highest mountain in Western Japan and the island of Shikoku.
Outline
Mount Ishizuchi is the hig ...
on
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
. It is the highest mountain in western Japan and the highest mountain in
Shikoku
is the smallest of the four main islands of Japan. It is long and between wide. It has a population of 3.8 million (, 3.1%). It is south of Honshu and northeast of Kyushu. Shikoku's ancient names include ''Iyo-no-futana-shima'' (), ...
.
In the western end of the Sea is
Mimosusogawa Park (
:ja:みもすそ川公園) in
Shimonoseki
is a city located in Yamaguchi Prefecture, Japan. With a population of 265,684, it is the largest city in Yamaguchi Prefecture and the fifth-largest city in the Chūgoku region. It is located at the southwestern tip of Honshu facing the Tsush ...
. It commemorates the final stage of the
Genpei war
The was a national civil war between the Taira and Minamoto clans during the late Heian period of Japan. It resulted in the downfall of the Taira and the establishment of the Kamakura shogunate under Minamoto no Yoritomo, who appointed hi ...
between the feudal
Taira clan
The Taira was one of the four most important clans that dominated Japanese politics during the Heian, Kamakura and Muromachi Periods of Japanese history – the others being the Fujiwara, the Tachibana, and the Minamoto. The clan is divi ...
and
Minamoto clan
was one of the surnames bestowed by the Emperors of Japan upon members of the imperial family who were excluded from the line of succession and demoted into the ranks of the nobility from 1192 to 1333. The practice was most prevalent during th ...
(1180–1185).
Literature
Some sites along the Seto Inland Sea were featured in eighth-century Japanese literature, both in prose and in verse, including ''
Kojiki
The , also sometimes read as or , is an early Japanese chronicle of myths, legends, hymns, genealogies, oral traditions, and semi-historical accounts down to 641 concerning the origin of the Japanese archipelago, the , and the Japanese imperi ...
'', ''
Nihon Shoki'', and ''
Man'yōshū
The is the oldest extant collection of Japanese (poetry in Classical Japanese), compiled sometime after AD 759 during the Nara period. The anthology is one of the most revered of Japan's poetic compilations. The compiler, or the last in ...
''. Since some sites were used as places of exile, their feeling and landscape were evoked in
waka
Waka may refer to:
Culture and language
* Waka (canoe), a Polynesian word for canoe; especially, canoes of the Māori of New Zealand
** Waka ama, a Polynesian outrigger canoe
** Waka hourua, a Polynesian ocean-going canoe
** Waka taua, a Māor ...
. In fiction, in ''
The Tale of Genji'', Genji fled from Kyoto and resided in Suma (now a part of
Kobe
Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, w ...
) and
Akashi Akashi may refer to:
People
* Akashi (surname)
Places
* Akashi, Hyōgo
* Akashi Station, a Japanese railroad station on the Sanyō Main Line
* Akashi Strait
* Akashi Kaikyō Bridge, crossing the former
* Akashi Castle
* Akashi Domain
* Akashi, th ...
for two years.
In medieval literature, because of the
Genpei War
The was a national civil war between the Taira and Minamoto clans during the late Heian period of Japan. It resulted in the downfall of the Taira and the establishment of the Kamakura shogunate under Minamoto no Yoritomo, who appointed hi ...
, the Seto Inland Sea is one of the important backgrounds of ''
The Tale of the Heike
is an epic account compiled prior to 1330 of the struggle between the Taira clan and Minamoto clan for control of Japan at the end of the 12th century in the Genpei War (1180–1185). Heike () refers to the Taira (), ''hei'' being the ''on ...
'', particularly in its latter part.
In the Western world,
Donald Richie
Donald Richie (17 April 1924 – 19 February 2013) was an American-born author who wrote about the Japanese people, the culture of Japan, and especially Japanese cinema. Although he considered himself primarily a film historian, Richie also di ...
wrote a literary nonfiction travelogue called ''
The Inland Sea
''The Inland Sea'' is a 1991 American travel documentary directed by Lucille Carra. It is inspired by the 1971 travelogue of the same title written by Donald Richie. In the documentary, filmmaker Carra undertakes a similar trip across the island ...
'' relating a journey along the sea, beginning from the East at Himeji and ending at Miyajima in the West, close to Hiroshima, going from island to island, exploring the landscape, meeting and discussing with local people, as well as musing on Japanese culture, the nature of travel and of identity, and his own personal sense of identity.
In 1991, filmmakers
Lucille Carra Lucille Carra (born New York City) is an American documentary film director, producer, and writer. She is of Sicilian descent. All of her films have been seen on PBS and international television. Carra has a BFA in Film Production and an MA in Cinem ...
and Brian Cotnoir produced a film version of Richie's book, which further explored the region through interviews and images photographed by Hiro Narita. Produced by Travelfilm Company and adapted by Carra, the film won numerous awards, including Best Documentary at the Hawaii International Film Festival (1991) and the Earthwatch Film Award. It screened at the Sundance Film Festival in 1992.
NY Times review
/ref>
Koushun Takami
is a Japanese author and journalist. He is best known for his 1999 novel '' Battle Royale'', which was later adapted into two live-action films, directed by Kinji Fukasaku, and three manga series.
Takami was born on 10 January 1969 in Amaga ...
's novel '' Battle Royale'' took place on a fictional island in the Seto Inland Sea.
A critical plot element of the Japanese series ''Fafner in the Azure
is a Japanese mecha anime franchise created by Xebec in collaboration with Starchild Records. The story focuses on a group of children who pilot the titular Fafners in an escalating war against giant aliens called Festum. The first s ...
'' is an alien life form discovered at the bottom of this sea known as the Seto Inland Sea Mir.
References
External links
Seto Inland Sea National Park Official site
Setonaikai National Park
- by JNTO
*
{{Authority control
Seas of Japan
Seas of the Pacific Ocean
Landforms of Ehime Prefecture
Landforms of Yamaguchi Prefecture
Landforms of Hiroshima Prefecture
Landforms of Okayama Prefecture
Landforms of Hyōgo Prefecture
Landforms of Fukuoka Prefecture
Landforms of Ōita Prefecture
Landforms of Kagawa Prefecture