A blissfully cool 10 degrees Celsius is the perfect temperature for scrambling down an old mine shaft vigorously and then sailing across the longest underground zipline in the world—so says Go Below Underground Adventures operations manager Mike Morris, from Wales.
Several days a week, he clips onto a safety wire and makes the 1,375-foot descent below the surface in an abandoned slate mine near Lake Level where he brings guests to stay in the world’s deepest underground hotel suites—which are all comfortably well-heated.
“Even on a freezing cold day, it’s still going to be 10 degrees [50 degrees Fahrenheit] down there,” Mr. Morris, 33, told The Epoch Times, speaking of the subterranean property of thermal inertia. “And if it’s on a boiling hot day, it’s still 10 to 12 degrees, which is quite a pleasant temperature, maybe a little bit chilly.”
The mine is in the tiny Welsh village of Tanygrisiau, near the quiet, rustic town of Blaenau Ffestiniog, also known as the slate capital of the world. If the chalkboards at your old elementary school did not come from here, your neighbor’s slate roof might well have.
The first heavy equipment began operating here around 1860. Since then, the mine, called Cwmorthin, was quarried by a succession of slate companies up until the early 1990s when operations came to an end. The adventure company then took over the lease.
Today, you can still find antique tins and pieces of china pottery—the Welsh miners downed copious amounts of tea—left scattered throughout the mine. Spelunking enthusiasts like Mr. Morris and his colleagues are now passionate about this history—and about sharing it with visitors.
For the past 14 years, they have taken clients into the slate mines, and that’s how the idea for Deep Sleep, the world’s deepest accommodation, was conceived in 2018. Down at the lowest point, the guides heard feedback from their customers: “Wouldn’t it be great to sleep in the mine?”
“That made us think, ‘Okay, you know what, there might be a market for this,’” Mr. Morris said, adding that it was “a gamble really” with a laugh. “It would have been unfortunate if it didn’t pay off.”
It was also a mammoth challenge for them to implement their plan for a “glorified camping experience” at the bottom of the mine. Getting one cabin down there was one thing, but they ended up building four lovely cabins, fully furnished with electricity, water, and even Wi-Fi.
One can only try to picture them toting furnishings along on their precipitous climbs; stringing timber, refrigerators, toilets, and kitchen sinks down swaying zip lines from above to the bottom.
“All of that had to come down the route that we would take people on trips, which was probably the most challenging thing,” Mr. Morris said.
It wasn’t simply like a few flights of stairs. The levels are labeled according to letter: “A” marks ground level, and level “G”, the lowest level, is where their hotel site is situated. Actually, there were depths below this in bygone days; Cwmorthin once descended all the way to level “S”, though the collapses of unstable tunnels and constant flooding have since sealed off the deepest parts of the mine.
Another challenge of building the deepest hotel in the world was keeping a project of such scope quiet while construction was going on and customers were milling about. Then the global pandemic threw a spanner in the works, putting Deep Sleep into a deep slumber for a few years, though things really turned around once operations began running.
“It fully opened towards the tail end of last year,” Mr. Morris said. “It’s been a massive success since—the phone’s not stopped ringing about it really.”
Business has been so good, actually, that Go Below went from hosting nights on Saturdays only to also including most Fridays for visitors wanting to stay in the mine. “We asked them all for feedback, and everybody said it was absolutely great,” Mr. Morris said.
For potential mine adventurers thinking of visiting, a trip to Deep Sleep might look something like this:
You arrive at Tanygrisiau, aboveground, around 5 p.m. and meet the trip leader, because they “can’t have people wandering around in the mine on their own,” Mr. Morris said. “It’s not a very safe environment—which is part of the fun, but it does mean that they need a trip leader with them.”
The trek into the mine certainly isn’t for the faint of heart, he assures us, and a reasonable level of physical fitness is expected.
You will don helmets, a harness, and “Wellington” boots. Then you begin your descent.
There are various obstacles that will need to be overcome, such as the old decaying bridge with a pitch-black drop that Mr. Morris describes as “quite terrifying.”
It’s a fatal drop of over 100 feet, but, he said with assurance, “You'd be clicked into a safety system the whole time, so you’re never at any risk of falling or getting hurt or anything like that.”
Daily line inspections and more official weekly checks ensure all the carabiners and ropes are up to safety standards. The route that they had chosen has undergone a professional mine inspection.
There is a flooded section where one will balance while crossing some pipes that have been installed, before descending the “waterfall climb.”
The arduous yet rewarding journey to the accommodations usually takes around 2.5 hours, and travelers are then welcomed warmly at the bottom with a nice cup of tea to calm the nerves.
“They will be greeted by one of our other members of staff who will have been down there just making sure that the place is nice and warm because it’s all heated,” Mr. Morris said. “All the rooms are heated.”
If the jaunt to Cwmorthin slate quarry sounds inviting, Mr. Morris wants potential guests to know something: “Know what you’re getting yourself in for,” he said, adding that “it’s definitely a bit out of the ordinary.”
The history of how miners lived in the depths leaves many guests dreamy-eyed. The guides will do their best to share some of the wonder they have for the old slate mine.
What should you bring?
“Make sure you bring your sense of humor with you because it’s going to be a fun trip for sure,” the guide said. “And, yeah, bring your adventurous side with you and just relax and enjoy it.”
