Llechwedd Slate Caverns

Llechwedd opened in 1846 and worked slate on a huge scale, roofing much of Britain from chambers cut hundreds of metres into the mountain; the Welsh slate landscape of northwest Wales, including these workings, was inscribed by UNESCO in 2021. The deep mine tour descends on a cable railway at a gradient of about one in one point eight, the steepest in Britain, into a chamber system where guides explain the conditions men worked in by candlelight, paid by the ton of finished slate rather than by the hour. Above ground, Bounce Below strings trampolines and slides through a disused chamber lit in colour, and Zip World Titan runs zip lines over the tips. Blaenau Ffestiniog itself is ringed by grey spoil that was deliberately excluded from the national park boundary.

What you actually see

• The cable railway - Britain's steepest, descending into the deep mine.
• The worked chambers - vast voids cut by hand and explosive from 1846.
• Bounce Below - trampolines and slides strung inside a disused chamber.
• The slate landscape - a UNESCO-inscribed industrial terrain of tips and terraces.

When to go

Year-round; the mine holds a constant cool temperature so a coat is needed in summer. Underground activities book ahead and fill in school holidays. Blaenau's weather is famously wet, which matters less here than elsewhere.

Honest expectations

Each activity is separately ticketed and the total mounts quickly. The deep mine tour is cold, damp and involves the steep railway both ways. Bounce Below is aimed at families and is loud. The town outside is bleak, which is part of the story.

Nearby

The Ffestiniog Railway runs down to Porthmadog; Snowdonia surrounds the town.