"Marine theatre" ("Marinetoneel" in Afrikaans) is a general term used by F.C.L. Bosman 1980) to refer to various kinds of amateur theatre and other performances specifically undertaken by officers and by sailors (both on board ship and on land), especially in the 19th century.
Examples from South Africa
1608: According to Jill Fletcher (quoting Keeling and Bonner) what would perhaps qualify as the first example of marine theatre was a production of (scenes from) Hamlet that Captain William Keeling had performed on board his British East India Company's ship the Red Dragon, off the coast of Southern Africa in 1608, while on his way to the Cape of Good Hope.
1865: Charity performances of The Dream at Sea and Cool as a Cucumber were performed in aid of victims of the great storm of May, by the amateurs of H.M.S. Valorous in the Theatre Royal, Cape Town, on 1 and 2 June - playing to sellout houses.
1869-1872: The amateurs of the H.M.S. Rattlesnake apparently performed a number of times, playing inter alia in the Oddfellows Hall, Cape Town, on 7 October 1869 in aid of the "Sailor's Home" and in the Dockyard Theatre, Simonstown, in July 1872.
See also Garrison Theatre