Gilligan's Island is a typical unnamed and uncharted South Pacific tropical Island with beaches, mountains, jungles and a lagoon. It is where the seven passengers aboard the S.S. Minnow were marooned. It is also in the target line of the United States Air Force experimental missile range. The neighboring islands are inhabited by Natives that practice rites similar to Voodoo (a Caribbean religion from Africa) and collect the heads of rival tribes. There are a few friendly tribes often visited by sailors who explore the islands in the area. Gilligan saves a female native from one tribe while a local chieftain appears on the island in search of a White Goddess.
Although unnamed, Mr. Howell once tries calling it "Howell Hills," but this reference doesn't seem to catch on. The castaways just refer to it as "the island." It is said to be "a tiny island somewhere in the South Pacific." Though, throughout the series, such features as quick-sand, an active volcano, staggering mountains and not to mention extensive jungles add to it all. It's never explained how all these landmarks fit on such a small island. However, it does have the trappings of paradise, even Ginger at one point calls it a great place to film a movie following the glue incident. Although it is described as "a tiny island," it probably ranges in size somewhere between 200 to 400 square miles (500 to 1000 square kilometers) or the size of a typical South Pacific Island.
The island's position is also uncertain as the Skipper and the Professor have different ideas on its position. On one occasion, the island's position is said to be about 140 longitude by 10 latitude as according to the Professor. However, several months later, the Skipper tells surfer Duke Williams that their position is approximately 110 longitude by 10 latitude. Furthermore, when the US Navy see Gilligan flying over the island, the location is reported as 250 miles south of Hawaii; so possibly, during their time on the island, the Skipper and Professor are constantly refining and recalculating their position based on storm reports through the radio. Despite being reportedly "uncharted," it is known the island was used as a temporary landing field and air field for the Army Air Corp during World War Two, due to the Quonset hut and Air Force planes found much later on the island. During a Coast Guard search, one Coast Guard pilot mentions that he knows about the island not being on the map and convinces the other pilot to fly over it. During his time on the island, Mr. Howell repeatedly mentions his plans and intentions to make the island a resort; he finally succeeds at this with the creation of The Castaways Resort.
- crows in The Sound of Quacking
- fruit bats
- orangutan in Our Vines Have Tender Apes
- owl in The Hunter
- parrots in New Neighbor Sam, Don't Bug the Mosquitoes and Voodoo
- six-foot spider
- wild boar in Where There's a Will
- woodpecker in Two on a Raft and Hair Today, Gone Tomorrow
- big rock on north side near a hollow log in The Kidnapper
- Caves in numerous episodes
- cliffs in Take a Dare, Man With a Net and Agonized Labor
- a gold mine in The Big Gold Strike
- the lagoon
- a mountain range in Man With a Net
- a mud bog in High Man on the Totem Pole
- a quicksand pit in Where There's a Will and Man With a Net
- statue of a wooden idol on south end in The Kidnapper
- volcano in Operation: Steam Heat and Man With a Net (mentioned only)
- the waterfall
- freshwater (Water Water Everywhere)
- keptiburra/captivora berries (Topsy-Turvy)
- mind-reading seeds (Seer Gilligan)
- natural gas (Gilligan Meets Jungle Boy and Sorry, You've Been Disconnected)
- oleander (Not Guilty)
- rubber trees (Sorry, You've Been Disconnected)
- scheelite phosphorescent rocks (Gilligan Goes Gung-Ho)
- trigonella berries (Bang! Bang! Bang!)
- wasubi berries (Agonized Labor)
- Three different real-life separate islands were used in the opening credits of the series. The First season black-and-white version was Sandy Cay, a 3-acre island near the Bahamas in the Caribbean. It is now one of the many destinations featured on Disney Cruise Lines, most likely being Castaway Cay, but it is unknown which of the islands were filmed. The island seen from a distance during the Second and Third Season color episodes was Mokuoloe ("Coconut Island") near Oahu which covers 28-acres in size. The pilot, however, was filmed at Moloa'a beach on the north of Kaua'i in Hawaii, and the Second and Third episode opening credits scenes that show the wreck of the SS Minnow on the lagoon, an obvious continuity error, was the flooded parking lot at the studio in Los Angeles.
- Three layouts are shown of the island through the series. The photos at upper left from Forward March and Man With a Net episode show identical maps of the Island except the waterway from the lagoon bends counter-clockwise instead of clockwise as it does on the actual exterior set. In Splashdown, a different map of the island from space is shown which leaves out the mountains and clearings. Apparently, there is a small lagoon a short walk from the hut area and a wide beach where the S.S. Minnow was shown wrecked in the First Season.
- The beach scenes in Two on a Raft were filmed at Zuma Beach near Malibu, California.