Palisades Park

Palisades Park is a park with a couple of caves called "Clark Caves", where people go spelunking.

Clark Caves
Mr. Ratburn assigns his class to build a replica of a cave since they are going on a field trip to Palisades Park. Arthur thinks that he might be braved of caves. He tells D.W. and his friends, and they don't want to make fun of him anymore.

The Cave that Mr. Ratburn's Class Visits
At the park a tour guide tells them about the cave they will be going into.

Inside the cave most of the kids are fine (even Arthur), but after Francine and Mr. Ratburn see bats, they get scared and leave the cave as quickly as possible. In the end everybody ends up making fun of Francine.
 * It started forming over 10 million years ago
 * It is over 5 miles long.
 * At its deepest point it is 1,500 feet.
 * Bats and fungi live inside.