When a decaying Russian satellite crashes on the island, the Professor uses a key component for a barometer. With that device, he learns that a massive wave is going to swamp the island. In desperation, the castaways lash their huts together into one structure in order to have any chance to ride the disaster out. The wave strikes the island and the hut is swept out to sea. Once there, Gilligan accidents starts a fire trying to cook a meal and nearly burns the floating hut down. Occupied with stopping the fire, the gang fails to notice that the smoke caught the attention of a naval helicopter who summoned a ship to rescue the castaways. In triumph, they return to Hawaii, only to learn that things have changed over the years and they will have trouble fitting in. To further complicate matters, two Russian spies are after that key component that Gilligan now wears as a necklace. At the end the castaways plan a reunion trip back to Gilligan's Island, and wouldn't you know it, they get stranded again.
Stuck on the same island as before, the castaways find an abandoned World War II bomber that the Professor is able to repair and fly. However, in the attempt to fly to Hawaii, Gilligan falls out and has to parachute down to the island. Against their better judgement, the gang decides to return the island to get him. Unfortunately, the engines collapse after they land, which means that Gilligan had screwed up yet another escape attempt. Their despair is quickly dispelled when a U.S. Navy captain appears saying that their plane was detected on radar long enough for them to follow it to the island. A year later, the island is now a tropical resort spot fully linked to Civilization, and the castaways work as the staff of a kind of island Love Boat as they work to entertain the various guests they receive.
The famous Harlem Globetrotters crash land on Gilligans Island, immediately dispatching a terrifying 'shark' by throwing basketballs at it. A mad doctor and his accomplice plan to take over the island for its rich energy supply by scaring off Gilligan and his buddies, but it soon settles to a basketball match between the doctors robots and the aforementioned Globetrotters.