Deep in a former Welsh slate quarry mining cavern twice the size of St. Paul’s Cathedral, children and adults alike gleefully jump up and down on a system of netting suspended from the walls. Bounce Below, the world’s largest underground trampoline, will open to the public July 3rd in the mining town of Blaenau Ffestiniog.

Operated by Zip World, the new tourist attraction features three massive trampolines that ascend from twenty feet to 180 feet above the bottom of the cavern, with ten-foot net walls preventing anyone from falling over the edge. Customers get dressed in cotton overalls and put on helmets, then board a train that travels deep into the mountain.

They disembark to the sight of the trampolines within the colorfully lit space. Each trampoline is linked by a slide for descending and a net walkway for getting back up. The largest slide is 60 feet long. A spiral staircase leads to the other side of the railway line.

Workers prepared the space by carrying about 500 tons of rubble out of the cavern, the task illuminated with portable lamps. The mining of slate in Wales dates back to Roman times and the industry peaked in 1898 with 17,000 employees, but by the end of World War II, the introduction of new roofing materials led to many of the mines closing.

Pedestrian roads would be a lot more fun if they were bouncy. Maybe that’s why Salto Architects decided to complete this unusual installation, a 557-foot-long (170 meter) trampoline walkway that runs through the woods of Russia. ‘Fast Track’ eschews the entirely practical nature of most roadways, choosing to infuse it with an element of fun that encourages users to pause and laugh for a while.

Bouncing along the trampoline gives pedestrians more time to take in and appreciate their surroundings as they walk, leading them to interact with it in a different way. The Estonian architecture studio sought to “create intelligent interactive spaces that emotionally correspond to its local context.”

The walkway was built for the Archstoyanie Festival in Russia, giving attendees a fun and interactive way to get from one end of the event space to the other.

The project is reminiscent of a recently unveiled concept by studio AZC for an inflatable bridge in Paris that is more recreational than practical. While this approach to infrastructure isn’t likely to spread on a large scale, for obvious economic and efficiency reasons, it’s a nice change of pace as a temporary installation.