While flying a routine mission for the U.S. Navy from his aircraft carrier, an emergency causes Lieutenant Robin "Rob" Crusoe (Van Dyke) to eject from his F-8 Crusader into the ocean. Crusoe drifts on the ocean in an emergency life raft for several days and nights until landing on an uninhabited island. He builds a shelter for himself, fashions new clothing out of available materials, and begins to scout the island, discovering an abandoned Japanese submarine from World War II. Scouring the submarine, Crusoe also discovers a NASA astrochimp named Floyd, played by Dinky.