| Term | Definition |
| submersible | a craft that operates underwater |
| crustacean | hard-shelled animal with jointed parts, lives mostly in water |
| tentacles | long, narrow, elastic limbs of an animal used to grab or feel things |
| menagerie | collection of wild animals |
| unfathomable | impossible to measure |
| oceanographers | scientists who specialize in the study of the sea |
| hydrothermal vent | source of extremely hot water where many sea creatures thrive |
| bioluminescence | the emission of light from living organisms |
| gelatinous | having the nature of, or resembling jelly |
| tether | rope which an object is fixed to in order to limit its range of motion |
| mesopelagic | animals that are living in the "middle ocean" between 600-3,000 feet deep |
| undulates | to move in a smooth wavelike motion |
| panoramic | wide view of an area in all directions |
| sparse | not thick or dense, but thin or few |
| starboard | the right-hand side of a ship or plane as it faces forward |