Talk about going down for a nap.
A lodging located inside a former Victorian-era slate mine in North Wales is billed as the world’s deepest overnight accommodation.
Aptly named Deep Sleep, the cluster of four cabins and one double bedroom (pictured above) carved from a cavern wall offer subterranean slumber at an astonishing 1,375 feet below the surface.
For some context, the height of the Shard in London is 1,016 feet. If you somehow managed to fit that skyscraper into this Welsh mine, you could stack Big Ben’s tower (315 feet tall) on top, with room left over to stand King Charles, both his sons, both of their wives, and Queen Camilla on one another’s shoulders—and the topmost royal’s head still wouldn’t pop out of the mineshaft. Though wouldn’t it be nice to see them all working together as a family again?
Set amid the craggy peaks, forests, and waterways of the Snowdonia region in northwest Wales, the underground lodging requires an adventure to reach your room. Starting from the town of Blaenau Ffestiniog, overnighters are led by guides with Go Below Underground Adventures on a 45-minute hike into the mountains.
After gearing up with helmets, lights, and harnesses, groups then make a steep and challenging 1-hour descent into the mine with assistance from guides, who point out notable sights along the way and share historical info about the miners who once worked here.
(Credit: Go Below Underground Adventures)
Once you’ve reached the Deep Sleep site, you’ll check into either an underground cabin (each of which has two single beds) or the grotto room, carved from the slate walls of the mine and outfitted with a double bed.
There is battery-powered electric lighting, a dry toilet, running tap water, and even Wi-Fi down there—though no cell phone reception. The average temperature in the deepest chamber is about 10 degrees Celsius (50 Fahrenheit); cabins are insulated but you’ll still want to wear warm clothing.
Guides spend the night at the site, too, so you don’t have to worry about being stuck there by yourself. According to Go Below, independent mine engineers regularly conduct safety inspections.
(Deep Sleep underground cabins at Go Below Underground Adventures in North Wales | Credit: Go Below Underground Adventures)
The company advises that the experience requires a “moderate level of fitness and agility,” involving several hours of “walking, scrambling, ducking, and balancing.” The minimum age requirement is 14, and minors must be accompanied by an adult.
Launched in April 2023, the experience is offered once a week, from Saturday evening through Sunday morning. The price for a cabin sleeping two guests is £399 ($531); the grotto goes for £599 ($797). Both rates include accommodations for two and an “expedition-style” dinner (with vegan and vegetarian options available) as well as a light breakfast for each participant.
To see availability and find booking details, visit Go Below’s website.
An earlier version of this story, published June 11, 2023, has been updated for summer 2025.
