Maritime geography is a collection of terms used by

naval A navy, naval force, military maritime fleet, war navy, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operatio ...

military units to loosely define three maritime regions: brown water, green water, and blue water.

Definitions

The elements of maritime geography are loosely defined and their meanings have changed throughout history. The USA's 2010 Naval Operations Concept defines blue water as "the open ocean", green water as "coastal waters, ports and harbors", and brown water as "navigable rivers and their estuaries". Robert Rubel of the US

Naval War College The Naval War College (NWC or NAVWARCOL) is the staff college and "Home of Thought" for the United States Navy at Naval Station Newport in Newport, Rhode Island. The NWC educates and develops leaders, supports defining the future Navy and associa ...

includes bays in his definition of brown water, and in the past US military commentators have extended brown water out to from shore. During the

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

, green water denoted those areas of ocean in which naval forces might encounter land-based aircraft and brown water, land-based artillery. The development of long-range bombers with antiship missiles turned most of the oceans to "green" and the term all but disappeared. After the Cold War, US amphibious taskforces were sometimes referred to as the green-water navy, in contrast to the blue-water carrier battlegroups. This distinction disappeared as increasing threats in coastal waters forced the amphibious ships further offshore, delivering assaults by helicopter and tiltrotor from over the horizon. This prompted the development of ships designed to operate in such waters - the Zumwalt class destroyer and the

littoral combat ship A littoral combat ship (LCS) is either of two classes of relatively small surface vessels designed for littoral warfare in near-shore operations by the United States Navy. It was "envisioned to be a networked, agile, stealthy surface comba ...

s. Rubel has proposed redefining green water as those areas of ocean which are too dangerous for high-value units, requiring offensive power to be dispersed into smaller vessels such as submarines that can use stealth and other characteristics to survive. Under his scheme brown water would be zones in which ocean-going units could not operate at all, including rivers, minefields, straits and other choke points.

Regions

Brown water

The brown water environment starts from the shoreline through to the end of the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

. A

brown-water navy A brown-water navy or riverine navy, in the broadest sense, is a naval force capable of military operations in inland waters (rivers, lakes and inland seas) and nearshores. The term originated in the United States Navy during the American Ci ...

focuses on

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

operations and primarily takes a defensive role. "Brown water" or "brown ocean" is also used by

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

s to refer to

intertidal wetland An intertidal wetland is an area along a shoreline that is exposed to air at low tide and submerged at high tide. This type of wetland is defined by an intertidal zone and includes its own intertidal ecosystems. Description The main types of ...

s where the border between the ocean and dry land is not clear-cut.

Green water

The green water environment extends from the outer edge of the brown-water layer past any continental shelves,

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...

s and

island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been ...

s; perhaps a few hundred miles from shore. It is the most important maritime arena, including most coastal traffic and territorial waters, in which are found the great majority of a nation's maritime police, customs, environmental, and economic concerns. A

green-water navy A green-water navy is a maritime force that is capable of operating in its state's littoral zones and has limited competency to operate in the surrounding marginal seas. It is a relatively new term, and has been created to better distinguish ...

is capable of defense of its nation in depth and is a significant offensive force within its territory.

Blue water

The blue water environment extends from the outer edge of the green-water zone to the deep

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

of the world. A

blue-water navy A blue-water navy is a Navy, maritime force capable of operating globally, essentially across the deep waters of open oceans. While definitions of what actually constitutes such a force vary, there is a requirement for the ability to exercise Co ...

can project its nation's power throughout the world. The blue water policy was a long-standing political philosophy in Britain in the 18th century, which sought to advance British power through use of the

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

, although the term "blue water" did not appear until 1834.Shorter OED

References