The Sea Monster is a monster who appears in the episode "Prehibernation Week."
It is a big, elephant looking dark green monster with a long trunk and three eyes.
When Sandy ordered the other people in town to go look for SpongeBob she told the other people to check inside a moist cave she found. But the moist cave was revealed to be the elephant-like trunk of a sea monster of some sort.
- Due to having a trunk like an elephant, the Sea Monster could be an elephant fish, or possibly a spoof of it.