U.S.S. President Coolidge
Photograph by David Doubilet, National Geographic
Divers swim near a guntub on the sunken U.S.S. President Coolidge near Vanuatu's Espiritu Santo Island. Built in 1931 as a luxury cruise liner, the Coolidge was converted to military use during World War II. It sank in 1942 after inadvertently striking an American mine while approaching Espiritu Santo.