No, you’re not looking at an attraction inside a computer-generated theme park, but rather the world’s largest underground trampoline. It’s located inside a slate quarry cavern in the Welsh mining town of Blaenau Ffestiniog and was developed by Zip World. Officially known as Bounce Below, it’s slated to open in just a few weeks, complete with three giant trampolines suspended across the cave, ranging from 20 feet to 180 feet high. Continue reading for more pictures and information.

“We got the idea when my business partner saw this done in woods in France but this has never been done in a cavern, this really is a world first in Wales,” says Sean Taylor, owner of Zip World. “It’s a one hour activity where customers get dressed up in a cotton overall and given a helmet, they then jump on a train and travel inside the mountain.”