submarine, pigboat, sub, U-boat
['great white shark, white shark, man-eater, man-eating shark, Carcharodon carcharias', 'vault', 'megalith, megalithic structure', 'trimaran', 'suspension bridge', 'streetcar, tram, tramcar, trolley, trolley car', 'hippopotamus, hippo, river horse, Hippopotamus amphibius']