A large grey beast with heavy armour plating, the sea rhinoceros had a shark-like tail, a pair of horns on its snout, and another pair sprouting from its back. Rather than the legs of a regular rhino, the sea version sported flippers similar to those found on a fish or marine mammal. They were said to be attracted to the sounds of a Sea Bear attack, and could only be repelled by wearing anti-sea rhinoceros underwear. Anti-sea bear circles will not protect people from them.
Whilst out camping, SpongeBob, Patrick, and Squidward were the victims of a Sea Bear attack. The noise from this encounter attracted the attentions of a sea rhinoceros and proceeded to attack Squidward, the only member of the group unfortunate enough to not be wearing any anti-sea rhinoceros protection, much to his horror.