FREEDOM, Oklahoma - Alabaster Caverns is the largest natural gypsum cave in the world open to the public. Eighty feet underground, you'll see unique formations in the cave, which is home to five species of bats. Many visitors don't realize you can also spend the night in a smaller cave nearby.

“It's definitely out of the ordinary,” Craig Day says.

“It's out of the ordinary and it's memorable,” replies Kelli Thomas who is a tour guide.

“And it's not glamping is it?” jokes Craig.

“It's not glamping; there's nothing glamorous about it,” Kelli laughs.

But before you can hike to the cave, there are a few rules. First, you must have a minimum of three campers.

"If there was something that happened to one of you, one could stay with that person, the other could go for help," Kelli says.

There is a picnic area not far from the cave entrance, where you can fire up the grill. There is also a beautiful area on the edge of a canyon, where you can watch the sun set and the moon rise.

When you enter the cave, each camper must have three independent light sources. The cave has raised platforms to sleep on, where you can lay out your bed rolls.

This cave is called Water Cave for a reason. There’s a small waterfall at the back of the main chamber, creating a very damp environment, so sleeping in a tarp is a must. Getting the tarp in place is a little bit of a challenge on the slick platforms.

"Even though it's 55 degrees in here, I still worked up a sweat," says Craig. "They really recommend that you bring a camping pad with you, and I wish I would have followed that recommendation."

Besides the lights, other required necessities are hardhats and a first aid kit.

"Few people can say they've camped in a cave overnight," says Kelli.