Flipper & Lopaka S01E25 - The Monster from Quetzo

Dexter finds an old human diving suit and fills it with water, so he can walk on land and invade Iloka. To prevent Flipper from interfering, Dexter traps him in an underwater cave. The islanders try to fight off Dexter as he stomps around the island, but eventually flee in their canoes. Lopaka, Nola and Bolo remain on the island and defeat Dexter.