Zip World Llechwedd (Bounce Below)

Llechwedd occupies part of a still-partly-active slate quarry above Blaenau Ffestiniog, a town that grew to around 12,000 people at the peak of the slate industry before its long decline through the twentieth century. The caverns here are regularly counted among Wales’s top five visitor attractions, and Zip World has since added adventure activities inside and around the old workings.

The headline underground activity is Bounce Below: trampoline netting strung across multiple chambers of a cavern the operator describes as twice the size of St Paul’s Cathedral, with slides and a spiral walkway connecting the levels. Because it runs deep in the old quarry, the temperature stays a constant 6 to 8 degrees Celsius regardless of the season, which the operator markets as an all-weather activity. The same site also runs Titan, a seated zip line across two zones above the quarry workings, marketed as Europe’s first four-person zip line, plus a mine tour and underground golf.

It operates year-round apart from Christmas Day and Boxing Day. Betws-y-Coed and Blaenau Ffestiniog sit on the same Conwy Valley Line, so Llechwedd is reachable by train as well as by the roughly 12-mile drive over the Lledr Valley and through Dolwyddelan.

This suits anyone wanting an adventure activity that does not depend on conditions outside, and families with children too young for the more extreme zip lines elsewhere in the region. It does not suit anyone who dislikes enclosed underground spaces, since the whole experience takes place inside the old cavern workings. Velocity 2 at Penrhyn Quarry is the open-air alternative, 40 minutes north and considerably faster.