Gilligan's Island - Season 1 - Eps 18: X Marks the Spot
In a test of a deadly new missile, called "Operation Powder Keg," the Air Force chooses an "uninhabited island" which just happens to be Gilligan's Island. When the rocket lands and does not explode, Gilligan is chosen to crawl inside to defuse it, because he is the only one that can fit inside.
About Gilligan's Island

Title: Gilligan's Island
First Air Date: 1964-09-26
Last Air Date: 1967-04-17
Status: Ended
Rating: 7.431/10 (from 238 votes)
Language: EN
Seasons: 4
Total Episodes: 98
Network: CBS
Genres: Comedy, Family
Production Companies: United Artists Television, CBS, Gladysya Productions
Synopsis
The slapstick adventures of hapless Gilligan, long-suffering Skipper and their gang of mismatched castaways, all stranded on an uncharted desert isle after their tiny ship hit stormy weather.
Cast

Bob Denver
Gilligan

Alan Hale Jr.
Jonas "The Skipper" Grumby

Jim Backus
Thurston Howell, III

Natalie Schafer
Eunice "Lovey" Wentworth Howell

Tina Louise
Ginger Grant

Dawn Wells
Mary Ann Summers

Russell Johnson
Roy "The Professor" Hinkley