THAT is deep sleep! The deepest hotel in the world has opened 400 meters underground in a mine in Wales

Talk about a deep sleep.

A hotel claiming to be the deepest hotel in the world has opened its doors 419 meters below the mountains of Snowdonia in Wales.

This underground hideaway, with lodgings costing up to £550, is located deep in a chamber of the abandoned Cwmorthin slate mine and can only be accessed via a ‘steep and challenging’ route through the old mines.

It is called ‘Deep Sleep’ and consists of four private cabins with two single beds and a ‘romantic’ cave room with a double bed, dining area and toilet facilities with basic toilets and sinks.

The hotel, which describes itself as an ‘adventure experience in a remote camp’ and is run by the outdoor activities company Go downstairs, only open one night a week – Saturday night. Guests’ experience will begin at 5pm Saturday night at Go Below base near the town of Blaenau Ffestiniog where they will meet the guides who will lead them to the hotel.

Dubbed ‘Deep Sleep’, this underground retreat opened its doors to intrepid guests in April

The hotel is only accessible via a ‘steep and challenging’ route through the old workings of the Cwmorthin mine

First, they must trek up into the mountains for 45 minutes on a route that is sometimes ‘steep’ but is said to offer ‘beautiful’ views.

They stop at a cottage to ‘equip’ before their descent to the underworld with a helmet, lamp, armor and wellies.

What’s next? The hotel’s website states, “Then it’s time to bid farewell to the outside world and venture into the depths of the world’s largest and deepest abandoned slate mine.”

During the challenging route through the mine – which was worked from approximately 1810 to 1939 – guests will navigate old miners’ stairs, dilapidated bridges and scrambles.

The guide provides ‘a lot of historical information’ about the lives of the men and boys who worked in the mine along the way, with the descent to the hotel taking about an hour.

During the challenging route through the mine, guests navigate old miner’s stairs, dilapidated bridges and scrambles

The hotel consists of four private cabins with two single beds (upstairs) and a ‘romantic’ cave room

Guests enjoy a complimentary ‘expedition style’ dinner at the hotel’s picnic table

Describing itself as an ‘adventure experience in a remote camp’, the hotel is run by the outdoor activities company Go Below

Breakfast at the hotel, served at 8:00 AM, consists of ‘simple snacks’ and a hot drink

A guide provides ‘lots of historical information’ about the lives of the men and boys who worked at the mine during the descent to the hotel

When they arrive at Deep Sleep – the entrance marked by a large steel door – guests are welcomed with a hot drink and can enjoy a complimentary ‘expedition-style’ meal on the hotel’s picnic table.

“Then you are welcome to retire to your bed for a very deep sleep,” the hotel notes.

Year-round, the hotel has a temperature of 10 degrees Celsius (50 Fahrenheit), but the cabins are “quite cozy” thanks to the thick insulation lining their walls.

All electric lighting is low voltage and powered by 12v batteries. Surprisingly, it does have Wi-Fi, delivered via a mile-long Ethernet cable from a 4G antenna on the surface. There is even running water from a spring in the mine.

A private cabin for two people costs GBP 350 and an overnight stay for two people in the cave (pictured) costs GBP 550

The huts are said to be ‘quite cozy’ thanks to the thick insulation lining their walls

Guests can retire to their beds for a “very deep sleep,” the hotel notes

The guide and a member of the technical staff will spend the night together with the guests in the hotel

Surprisingly, the hotel has Wi-Fi, delivered via a mile-long Ethernet cable from a 4G antenna on the surface

The guide and a member of the technical staff will spend the night at the hotel, with breakfast – ‘simple snacks’ and a hot drink – taking place the next morning at 8 am.

Then it’s time to make the climb to the surface of the mine and reach daylight again.

The idea for the experience, which launched in April, came from Go Below founder Miles Moulding. It takes the crown of the world’s deepest accommodation from a hotel suite located 154 meters underground in Sweden’s Sala silver mine.

A private cabin for two people costs £350 and an overnight stay in the cave for two people is £550. Visit go-below.co.uk/deep-sleep.asp.