Bikini Atoll is the island that is directly above Bikini Bottom. It is in the northern Pacific Ocean and was said to have been used for more than 20 nuclear weapons tests between 1946 and 1958 for the U.S. It is currently under the jurisdiction of the Republic of the Marshall Islands, which gained independence from the United States of America in 1986.
 The Island
Seen at the beginning of almost every episode, Bikini Atoll is the marker of where the Bikini Bottom is located. It has been seen as just a small island with three Coconut Palm Trees. The only known locals are the two seagulls that attacked SpongeBob and his friends in Pressure. It seem to be one of the few places where SpongeBob can be without drying up. In many episodes that involved breaking the surface, or flying out of the water, the island is shown in the background. When SpongeBob and the gang break the surface, they become puppets on sticks, or live action characters. (SpongeBob turns into a real kitchen sponge, Patrick into a dried starfish, Sandy a squirrel puppet with a helmet, and so on.) Also, it appears in a scene in the SpongeBob theme song. Bikini Atoll in The SpongeBob SquarePants Movie and The SpongeBob Movie: Sponge Out of Water.
 The Real Island (or Atoll)
Bikini Atoll is one of the Micronesian Islands in the Pacific Ocean used by the military to test nuclear bombs; it has, at this time, been clean. It is said by some sources that the island model used in the show can be found in Tom Kenny's Pool.
There is the possibility that inspiration for SpongeBob could have been taken from the original story Binki Atoll, an island which got a small degree of fame after the many nuclear weapons tests there. The piece of clothing bikini derives its name from the island, and the show is rumored to be based off of the idea that the radiation caused by the detonation of the bombs resulted in giving the sea creatures the ability to talk.
- Because Bikini Bottom is within the seaspace of the Marshall Islands, this technically means SpongeBob and the rest of the Bikini Bottomites are of Marshallese nationality, although several episodes suggest that Bikini Bottom is a "nation" in its own right.
- This would also mean that Sandy is an American-Marshallese immigrant.