It is a light red submarine. There is a square-shaped hole on one of the walls of it for customers to order, and above it is a silver and gold awing. It has a big light blue window, and on top of the whole vehicle is a gray periscope.
Only one room existed in the submarine: the control room. There was enough room for a grill, the controls, and a serving window.
Before the episode occurred, this somewhat primitive submarine was used by an unknown animal. Somehow, it sunk and became useless to control.
Later, SpongeBob and Patrick find its periscope sticking out of the ground, dig it up, and take possession of it. At the Krusty Krab, Mr. Krabs has the idea of "bringing the Krusty Krab to the customers." He does so by converting the submarine into a mobile restaurant.
While SpongeBob and Patrick are trying to sell Krabby Patties, Plankton attempts to use his own traveling restaurant. The duo has some unusual ways of selling the Krabby Patties; they pay the customers to eat and make a deal to get the customers to eat burnt patties (rocks).
They accidentally fall into an abyss, but they unexpectedly sell Krabby Patties and Chum Patties from Plankton's restaurant to a sea monster. The monster chases Plankton, as he thinks the latter is dessert. SpongeBob attempts to get out of the abyss, but leave behind the heavy money, much to Mr. Krabs' surprise and horror. They manage to bring back several tons of colored rocks, however.
SpongeBob and Patrick's roles with this vehicle are somewhat reversed since SpongeBob is known to be a good cook even though he drives it, and Patrick is known to be a good driver even though he cooks the food.
SpongeBob is able to drive this submarine with discipline, yet he does not obey traffic lights and still crashes occasionally.
SpongeBob referrs to this machine as a UFO.
The steering wheel resembles a helm on a pirate ship.
Unlike other vehicles in Bikini Bottom, the Mobile Krusty Krab does not have any wheels, but is propelled.