Carl's Dad Caverns

Carl's Dad Caverns are caverns in Springfield, discovered by Carl's dad in 1956.

History
The Simpsons visit the caverns and when Bart realizes it's a nature walk, he tries to escape. Lisa gives him a nickel in a water bottle to entertain himself, while Homer tries to chip a piece of a rock. The rock falls into the ground and the Simpsons follow it, with Homer getting stuck in the hole.

Behind the Laughter
The name is a play on the.