Black Waters is a 64-page book supplement for the Great War at Sea series based on American plans to fight Germany. Most of the scenarios take place in the Caribbean Sea, but some actions are also placed in European waters.

There are 210 die-cut and mounted playing pieces, the same pieces that originally appeared in our now out-of-print U.S. Navy Plan Black. The Americans get ships ranging from three examples of the South Dakota class through the first American dreadnoughts, the South Carolina class, and the last of the American pre-dreadnoughts, the Connecticut class. There are also a pair of light carriers based on American plans to convert big armored cruisers.

The Germans add three of the GK4531 battle cruiser design and three representatives of the GK4251 battleship. And of course Germany receives an aircraft carrier, the proposed conversion of the huge liner Imperator. Argentina and Brazil receive part of their fleets, and there are two hypothetical Mexican battleships and small contingents from the Netherlands, Venezuela and Colombia.

The Caribbean map originally provided in Plan Black is included as well, making this supplement playable with the use of any other Great War at Sea game. There are over two dozen new scenarios, including the War Plan Silver set based on Woodrow Wilson's very serious threat to go to war with Italy in May 1919, plus revised versions of most of those originally seen in Plan Black.

This is not a stand-alone game; ownership of any Great War at Sea game is required to play some of the scenarios and Mediterranean, Jutland and Plan Red to play all of them. Also, Plan Gold is needed.