Complex sentence: Other entertainment was a brothel named "Pleasure Island," but was closed in 1941 and replaced by the submarine base. The 500-person mess hall doubled as a theater; tickets for military were 15 cents and 35 cents for civilian workers.
Split into simpler sentences: Other entertainment was a brothel named "Pleasure Island", but this was closed in 1941 and replaced by part of the submarine base. The tickets for military were 15 cents and 35 cents for civilian workers.