Maritime geography is a collection of terms used by

naval A navy, naval force, 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 operations and related functions. It inclu ...

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 associ ...

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 is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...

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

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 island ...

. A

brown-water navy The term brown-water navy or riverine navy refers in its broadest sense to any naval force capable of military operations in littoral zone waters. The term originated in the United States Navy during the American Civil War, when it referred t ...

focuses on coastal 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 atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...

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, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arch ...

s and

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An isla ...

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 Water police, also called harbor patrols, port police, marine/maritime police, nautical patrols, bay constables, river police, or maritime law enforcement or coastal police are police officers, usually a department of a larger police organizat ...

, customs, environmental, and economic concerns. A

green-water navy A green-water navy is a maritime force that is capable of operating in its nation'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 distingui ...

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 (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...

of the world. A

blue-water navy A blue-water navy is a 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 sea cont ...

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 United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against Fr ...

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

References