SpongeBob SquarePants is a sea sponge who lives in a pineapple under the sea, while his squid neighbor, Squidward Tentacles, lives in a moai. SpongeBob's other neighbor and best friend is a pink and highly idiotic starfish named Patrick Star, who lives under a rock. SpongeBob and Patrick live on both sides of Squidward Tentacles, a highly arrogant and egotistical octopus who dislikes them (especially SpongeBob) because of their annoying habits and is quite open about it.
SpongeBob's house-pet is a snail named Gary, who meows like a cat. Although Gary only speaks in a few episodes, the characters have shown an ability to understand him. In addition to this, underwater worms bark exactly like dogs, and are kept on chains. Jellyfish are the equivalent of bees; buzzing, "stinging" with electricity, and producing delicious "jelly", mocking the name "jellyfish", while still referring to a bee's honey. Clams act as birds, and fish act as the citizens of the community but generally are not important characters.
Although the citizens of Bikini Bottom live underwater, they mostly do not float, and gravity usually applies. A flurry of bubbles accompanies actions in many of the episodes to remind the viewer that the setting is underwater. However, the laws of physics in Bikini Bottom change somewhat from time to time, but mostly the water acts like air. For instance, characters can pour a glass of liquid, just as we do above the sea. Bikini Bottom has functional baths, pools, and toilets, and there are lakes and streams. In Battle for Bikini Bottom and a regular beach setting, Goo Lagoon, underwater liquid is referred to as goo. Once, during an episode set in a wilderness area, Patrick questions how a camp fire is possible on the lagoon bottom. As soon as the question is asked, the fire is immediately extinguished with a sizzle; however, this is only used for comedic effect, as fire is often used and seen. In another episode, Squidward sets up a functional electric fence. Strangely, all creatures in the series (except Sandy) are completely dependent on water for survival; if any sea creature on the show (even those that can survive above water, such as crabs) go on dry land, they begin to rapidly dehydrate and eventually suffocate.
SpongeBob works as a fry cook at the Krusty Krab, a fast-food restaurant, with Squidward as the cashier. The Krusty Krab is owned by Mr. Krabs, a greedy, penny-pinching crab and ex-Navy officer. Sheldon Plankton is Mr. Krabs's arch enemy who owns a low-rank fast-food restaurant called the Chum Bucket across the street from the Krusty Krab. The Chum Bucket has almost never had a customer, and Plankton spends most of his time plotting to steal the recipe for Mr. Krabs's popular Krabby Patty burgers. Only in the movie does he succeed; the formula is never actually revealed to the audience. This fact is mocked in the Krusty Krab Training Video episode, where the episode cuts off before the video reveals the recipe. Plankton's computer wife, Karen, alternately helps him in his schemes or bickers with him.
Sandy Cheeks is another friend of SpongeBob. She is a squirrel that lives in an underwater dome in Bikini Bottom. She was sent there to do research for her chimpanzee bosses. Sandy is from Texas, and speaks with a Texan accent. Sandy is an expert at karate. When not inside her tree-dome, she wears an astronaut-like suit because she cannot breathe in water. Sandy hibernates once a year.
Instead of cars, the residents of Bikini Bottom drive boats, known as "boatmobiles". SpongeBob is still in boating school after failing the driving test 58 times as it is revealed in one of the episodes.