The Main Drain (Place)
The Main Drain just appears in the episode The Main Drain. It can be found in the middle of the ocean.
Mr. Krabs tells SpongeBob and Patrick a story, in which two little children pull the giant plug and the whole ocean gets sucked into it, along with all the fish. Later Mr. Krabs says that it was Plankton and he who pulled the plug.
At the end, it is revealed that it was just a story told by SpongeBob.
The Main Drain is just a giant plug. There is a long rusty chain hanging on the plug.
- In reality, there is absolutely no such thing as a drain plug at the bottom of the sea.