World’s deepest underground rave set for Gwynedd slate mine
A limited group will descend 1,375ft into Cwmorthin mine on 15 Oct for a record‑breaking underground rave featuring DJ Roni Size.
The world’s deepest underground rave is slated to take place 1,375 feet beneath the surface of Gwynedd’s Cwmorthin slate mine on 15 October, with a handful of ballot winners set to descend into the historic tunnel for a record‑breaking dancefloor.
Organised by G‑SHOCK, the event will see participants navigate miners’ stairways, water‑logged passages and narrow ravines, using scrambles, zip lines and abseils before reaching a cavern that will be transformed into a temporary club.
At the bottom, DJ Roni Size will deliver a one‑off set designed for the subterranean chamber, while vibration transducers and specialist field‑recording equipment will broadcast the music through slate, mud and water, capturing the way the sound reverberates through the rock.
“Back in Bristol, we’d put on a party wherever we could, and some of the sounds came from what we called happy accidents, playing a track at the wrong speed, hearing something that sounds new but still works,” said Size. “Raves could take place in some crazy and unexpected places, on someone’s front lawn, down in tunnels, but what I’ve always done is play to the environment, and the crowd.”
He added that the underground setting will allow the set to become “a living, breathing thing that reflects the people there with you”, and that “by the time we’re 1,375 feet underground, everyone there will already have shared an adventure”.
The descent will be guided, with safety briefings and equipment checks carried out before participants enter the mine, which has been abandoned for decades but remains structurally sound for controlled access.
Only those who meet age, fitness and equipment requirements will be permitted to join the expedition, and places are allocated through a public ballot that closes on 9 October.
Winners will be notified shortly after the deadline and will receive detailed instructions on the required gear, including helmets, harnesses and waterproof boots, as well as a schedule for the underground route.
The event also serves as a record attempt, with organisers planning to document the entire descent and performance for submission to an independent body that recognises extreme achievements.
In addition to the rave, the participants will be the first to retrieve the GDG‑B100 MUDMAN product drop, a limited‑edition item that will be handed over in the same chamber before the wider public release.
Cwmorthin, situated in the heart of Snowdonia, was once a bustling slate‑working site that supplied material for roofs across the UK. Its network of tunnels, some flooded and others narrow, offers a unique acoustic environment that the organisers hope will add an unprecedented dimension to the music.
Local authorities have been consulted to ensure that the event complies with health and safety regulations, and a team of experienced cavers will be on hand throughout the night to monitor conditions and respond to any emergencies.
While the concept may sound like a novelty, the organisers stress that the rave is a serious endeavour aimed at pushing the boundaries of live music performance and exploring how sound interacts with natural underground spaces.
Tickets are not for sale; entry is solely determined by the ballot, and the limited capacity means that only a small, carefully selected group will experience the event.
Should the attempt be successful, it could set a new benchmark for underground gatherings, inspiring future events that blend adventure, technology and music in equally remote locations.
For those who miss the ballot, the event will be recorded and the footage made available online, offering a glimpse of what may become the most underground rave ever staged.