is a Japanese

national park A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...

, comprising areas of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Seto Inland Sea The , sometimes shortened to the Inland Sea, is the body of water separating Honshu, Shikoku, and Kyushu, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka Ba ...

, and of ten bordering

prefectures A prefecture (from the Latin word, "''praefectura"'') is an administrative jurisdiction traditionally governed by an appointed prefect. This can be a regional or local government subdivision in various countries, or a subdivision in certain inter ...

. Designated a national park in 1934, it has since been expanded several times. It contains about 3,000 islands, known as the Setouchi Islands, including the well-known

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 specifie ...

. As the park encompasses many non-contiguous areas, and covers a tiny proportion of the Inland Sea's total extent, control and protection is problematic; much of the wider area is heavily industrialized.

History

In 1934, when the area was envisioned as Japan’s first national park, it was far smaller than the expanse of today. Sixteen years later, in 1950, an expansion would seek to include other iconic sites in the region, bringing the total area roughly up to that of the present-day. Setonaikai is the biggest national park in Japan. In 1996,

Itsukushima Shrine is a Shinto shrine on the island of Itsukushima (popularly known as Miyajima), best known for its "floating" ''torii''.Louis-Frédéric, Nussbaum, Louis-Frédéric (2005)"''Itsukushima-jinja''"in ''Japan Encyclopedia'', p. 407. It is in the cit ...

(in Hiroshima prefecture) was registered as a “cultural site of world heritage” by UNESCO. It is known as one of the top three “most scenic spots” in Japan. In the 1960s and 1970s, a period of rapid economic growth was fueled in Japan, resulting in industrial contamination of the surrounding environment. In both fresh and ocean waters, unmonitored chemical runoff led to reduced water quality, mainly due to area farms’ use of synthetic fertilizers, pesticides, and herbicides. Detrimental levels of heavy metals began to rise, gradually affecting the natural food chain and greater ecosystem. Starting in the 1980s (and continuing on into the present day), water quality has been drastically improved; stricter regulations on chemical use and runoff have been enforced, as well as advancements in technology, namely a high-performance sewage disposal.

Climate

Setonaikai National Park maintains relatively mild temperatures throughout the year, so the climate is sometimes referred to as “Mediterranean”; in essence, the average temperature in winter rarely dips below freezing, or above 90°F (around 30°C) in the summer.

Sites

There are numerous sightseeing places in the national park. Kanmon Strait is one of them. It is between Honshu and Kyushu. A suspension bridge called the Kanmon Bridge spans the strait. In 1973, when it was opened for the public, it was the longest bridge (0.66 miles) in Asia. The Naruto whirlpools in Tokushima prefecture are tidal whirlpools in the Naruto Strait, a channel between Naruto and Awaji Island in Hyogo prefecture. The whirlpools, one of the prefecture’s major tourist attractions, are formed due to a narrow width (0.8 miles) of the strait and a water level difference of 5.6 feet between the Inland Sea and the Open Sea caused by the ebb and flow of the tide. It sometimes creates a whirlpool 100 feet in diameter.

Facilities

There are facilities where people can experience and learn about nature in the park. Mt. Rokko Nature Conservation Center and Mt. Rokko Guide House in Hyogo prefecture are places where people can find natural specimens of Mt. Rokko. Wasuzan Business Center is in Okayama prefecture. It stands on the top of Washuzan Mountain. It is near Seto-ohashi Bridge which is a series of ten bridges between Okayama and Kagawa prefectures. The total length is 8.1 miles (13.1 km). From the center, people can see the panorama of the bridge and the Inland Sea. It is possible to learn about the nature around the bridge and the history of the Inland Sea.”Facilities - Setonaikai National Park” Ministry of the Environment, 1 February 2012.

Natural areas

Islands This is a list of the lists of islands in the world grouped by country, by continent, by body of water, and by other classifications. For rank-order lists, see the #Other lists of islands, other lists of islands below. Lists of islands by count ...

: Awaji Island (part), Bōyo Islands, Ieshima, Miyajima,

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 ...

, Shiwaku Islands,

Shōdoshima Shōdoshima or is an island located in the Seto Inland Sea, Inland Sea of Japan. The name means "Island of Azuki bean, Small Beans". There are two towns on the island: Tonoshō, Kagawa, Tonoshō and Shodoshima, Kagawa, Shōdoshima, composing the ...

, Tomogashima *

Mountains A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher ...

Mount Rokkō is the name of a range of mountains in southeastern Hyōgo Prefecture, Japan. Outline There is no single mountain or peak called "Rokkō," although the highest peak of the mountains is called , (literally, ''the highest peak of the Rokkō ...

Mount Maya is a mountain in Kobe, Hyōgo Prefecture, Japan. This mountain is one of the major peaks of the Rokkō Mountains, and is the most popular peak for visitors on the West-Rokkō Mountains. Outline Mount Maya is one of the two centers in Rokk ...

Mount Noro is one of the most popular mountains around Hiroshima Prefecture, Hiroshima, Japan. It is part of the Setonaikai National Park. Mount Misen is famous for mountain climbing, trekking, camping and sakura, camellia, hydrangea, Color change in lea ...

Straits A strait is a water body connecting two seas or water basins. The surface water is, for the most part, at the same elevation on both sides and flows through the strait in both directions, even though the topography generally constricts the ...

: Akashi Strait,

Hōyo Strait The is the strait at the narrowest part of the Bungo Channel in Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of ...

Kitan Strait The or separates Awaji Island from Wakayama, Wakayama Prefecture, Japan and connects the Osaka Bay in the north to the Kii Channel in the south. The total width is 11 km, but the islands of Tomogashima reduce the distance to be spanned ...

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 bri ...

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 ...

* Other: Naruto whirlpools

Cultural sites

Shrines A shrine ( "case or chest for books or papers"; Old French: ''escrin'' "box or case") is a sacred space dedicated to a specific deity, ancestor worship, ancestor, hero, martyr, saint, Daemon (mythology), daemon, or similar figure of respect, wh ...

Itsukushima Jinja is a Shinto shrine on the island of Itsukushima (popularly known as Miyajima), best known for its "floating" ''torii''.Louis-Frédéric, Nussbaum, Louis-Frédéric (2005)"''Itsukushima-jinja''"in ''Japan Encyclopedia'', p. 407. It is in the cit ...

Kotohira-gū (also known as , , or Konpira Shrine in English) is a Shinto shrine in the town of Kotohira, Kagawa, Kotohira in Kagawa Prefecture, Kagawa, Japan. This shrine is patron of sea ship transport and sailors. It is a Kotohira Shrines, Kotohira Shrin ...

, Mekari Shrine *

Temples A temple (from the Latin ) is a place of worship, a building used for spiritual rituals and activities such as prayer and sacrifice. By convention, the specially built places of worship of some religions are commonly called "temples" in Engli ...

: Futago-ji, Yashima-ji

Related municipalities

The park crosses the borders of 55

cities A city is a human settlement of a substantial size. The term "city" has different meanings around the world and in some places the settlement can be very small. Even where the term is limited to larger settlements, there is no universally agree ...

, 14

towns A town is a type of a human settlement, generally larger than a village but smaller than a city. The criteria for distinguishing a town vary globally, often depending on factors such as population size, economic character, administrative stat ...

, and one

village A village is a human settlement or community, larger than a hamlet but smaller than a town with a population typically ranging from a few hundred to a few thousand. Although villages are often located in rural areas, the term urban v ...

: * Ehime: Ikata, Imabari, Kamijima,

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 is also Shikoku's largest city. , the city had an estimated population of 505,948 in 243,541 h ...

, Ōzu, Saijō, Yawatahama *

Fukuoka is the List of Japanese cities by population, sixth-largest city in Japan and the capital city of Fukuoka Prefecture, Japan. The city is built along the shores of Hakata Bay, and has been a center of international commerce since ancient times. ...

Kitakyushu is a Cities of Japan, city located in Fukuoka Prefecture, Japan. As of June 1, 2019, Kitakyushu has an estimated population of 940,978, making it the second-largest city in both Fukuoka Prefecture and the island of Kyushu after the city of Fuk ...

Hiroshima is the capital of Hiroshima Prefecture in Japan. , the city had an estimated population of 1,199,391. The gross domestic product (GDP) in Greater Hiroshima, Hiroshima Urban Employment Area, was US$61.3 billion as of 2010. Kazumi Matsui has b ...

Etajima , also called , ''Nomijima'', ''Nomi Island'', or is an island in Hiroshima Bay located in southwestern Hiroshima Prefecture, Japan. The mess with island name originates from the ancient (and possibly legendary) strait at now town . Geography T ...

, Fukuyama, Hatsukaichi, Higashihiroshima,

Kure is a city in the Hiroshima Prefecture, Japan. , the city had an estimated population of 208,024 in 106,616 households and a population density of 590 persons per km2. The total area of the city is . With a strong industrial and naval heritage, ...

, Mihare,

Onomichi is a Cities of Japan, city located in Hiroshima Prefecture, Japan. , the city had an estimated population of 129,314 in 64055 households and a population density of 450 people per km². The total area of the city is . Geography Onomichi is loca ...

, Ōsakikamijima, Ōtake,

Saka The Saka, Old Chinese, old , Pinyin, mod. , ), Shaka (Sanskrit (Brāhmī): , , ; Sanskrit (Devanāgarī): , ), or Sacae (Ancient Greek: ; Latin: were a group of nomadic Iranian peoples, Eastern Iranian peoples who lived in the Eurasian ...

Takehara file:Takehara City.jpg, 270px, Panorama of Takehara City center file:Takehara city center area Aerial photograph.2010.jpg, 270px, Aerial photograph of Takehara City center file:Taketsuru house Takehara.jpg, 270px, Taketsuru house in Takehara histo ...

* Hyōgo: Aioi, Akashi, Akō, Ashiya, Awaji,

Himeji 260px, Himeji City Hall is a city located in Hyōgo Prefecture in the Kansai region of Japan. , the city had an estimated population of 525,682 in 227,099 households and a population density of 980 persons per km2. The total area of the city is ...

Kobe Kobe ( ; , ), officially , is the capital city of Hyōgo Prefecture, Japan. With a population of around 1.5 million, Kobe is Japan's List of Japanese cities by population, seventh-largest city and the third-largest port city after Port of Toky ...

, Minamiawaji,

Nishinomiya 270px, Nishinomiya City Hall 270px, Aerial view of Nishinomiya city center 1985 270px, Hirota Shrine is a city located in Hyōgo Prefecture, Japan. , the city had an estimated population of 484,368 in 218,948 households and a population density ...

, Sumoto, Takarazuka, Tatsuno * Kagawa: Higashikagawa, Kan'onji, Kotohira, Mannō, Marugame, Mitoyo,

, Sakaide, Sanuki,

, Tadotsu,

Takamatsu file:Takamatsu City Hall.jpg, 270px, Takamatsu City Hall file:Takamatsu city center area Aerial photograph.2007.jpg, 270px, Aerial view of Takamatsu city center file:Takamatsu200910cut.JPG, 270px, View from Yashima to Takashima port is a capital ...

, Tonoshō, Zentsūji * Ōita: Bungotakada, Himeshima, Kunisaki, Ōita *

Okayama is the prefectural capital, capital Cities of Japan, city of Okayama Prefecture in the Chūgoku region of Japan. The Okayama metropolitan area, centered around the city, has the largest urban employment zone in the Chugoku region of western J ...

: Asakuchi, Bizen, Kasaoka,

Kurashiki is a city located in Okayama Prefecture, Japan. , the city had an estimated population of 478,651 and a population density of 1300 persons per km2. The total area of the city is . Geography Kurashiki is located in the south-central part of Okay ...

, Setouchi, Tamano *

Tokushima is a Prefectures of Japan, prefecture of Japan located on the island of Shikoku. Tokushima Prefecture has a population of 682,439 (1 February 2025) and has a geographic area of 4,146 Square kilometre, km2 (1,601 sq mi). Tokushima Prefecture b ...

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. T ...

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, a national university in Wakayama, ...

* Yamaguchi: Hikari, Hirao,

Hōfu file:Hofu City Hall 2021-08 ac (2).jpg, 270px, Hōfu City Hall file:Hofu city center area Aerial photograph.2010.jpg, 270px, Aerial photograph of central Hōfu file:Hofu-tenmangu, roumon-1.jpg, 270px, Hōfu Tenman-gu is a Cities of Japan, city ...

Iwakuni file:20100724 Iwakuni 5235.jpg, 270px, Kintai Bridge file:Iwakuni city center area Aerial photograph.2008.jpg, 270px, Iwakuni city center is a Cities of Japan, city located in Yamaguchi Prefecture, Japan. , the city had an estimated population of ...

, Kaminoseki, Kudamatsu,

Shimonoseki file:141122 Shimonoseki City Hall Yamaguchi pref Japan01s3.jpg, 260px, Shimonoseki city hall is a Cities of Japan, city located in Yamaguchi Prefecture, Japan. , the city had an estimated population of 248,193 in 128,762 households and a pop ...

Shūnan file:Tokuyama district Shunan city Aerial photograph.2008.jpg, 270px, Shūnan city center is a Cities of Japan, city in Yamaguchi Prefecture, Japan. , the city had an estimated population of 137,019 in 6828 households and a population density o ...

Suō-Ōshima is a town and an island located in Ōshima District, Yamaguchi Prefecture, Japan. Suō-Ōshima was formed on October 1, 2004 from the merger of the former towns of Ōshima, Kuka, Tachibana and Tōwa, all from towns of Ōshima District. As ...

Tabuse 270px, Umashima is a town located in Kumage District, Yamaguchi Prefecture, Japan. , the town had an estimated population of 14,411 in 6947 households and a population density of 290 persons per km2. The total area of the town is . Geography ...

, Yanai