Dictionary 1. (a.) Being, acting, or growing, under water in the sea; as, submarine navigators; submarine plants\.2. (n.) A submarine plant or animal. Thesaurus Aqua-Lung U-boat U-boot Unterseeboot air cylinder aquascope bathyscaphe bathysphere benthoscope buried diving bell diving boat diving chamber diving goggles diving helmet diving hood diving mask diving suit drowned engulfed flooded immersed inundated periscope pigboat scuba snorkel sub subaqueous submerged submersed submersible sunken swim fins undersea underwater wet suit |