Regions

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Maritime geography is often discussed in terms of four loosely-defined regions: Riverine, brown water, green water, and blue water.

Riverine

The riverine environment consists of all navigable rivers of interest.

Brown water

The brown water environment consists of the littoral areas, from the coast and estuarial areas to perhaps a hundred miles from shore. It is the most important maritime arena, including all coastal traffic and territorial waters, in which are found the great majority of a nation’s maritime police, customs, environmental, and economic concerns.

A "brown water navy" focuses on coastal operations and takes a more defensive role in the navy.

Green water

The green water environment extends from of the outer edge of the brown-water zone past any continental shelves, archipelagos and islands; perhaps a thousand miles from shore.

Blue water

The blue water environment extends from the outer edge of the green-water zone through the global deep ocean.

Oceanography