Extreme hotels/ The world's deepest subterranean hotel room

The eerie hotel suite accommodates two and is situated 155 meters (509 ft) below the earth's surface, amidst winding tunnels and deep cavities (image: Sala Silvermine)

Deep within the dark tunnels and cavity shafts of an old Swedish silver mine, guests can sleep in the world's deepest hotel suite. The Sala Silvermine is located in Sala (120 km/75 miles from Stockholm) and is believed to date back to the Middle Ages. For a long period of time the mine was Sweden's largest source of silver, and is now home to an underground hotel room, dining experience, museum, live theater and numerous exploration activities.

The eerie hotel suite accommodates two and is situated 155 meters (509 ft) below the earth's surface, amidst winding tunnels and deep cavities. The suite is not suitable for claustrophobes, as the dark chamber features a double bed surrounded by three rock walls, candles, seating and little else.
Upon arrival, the daring guests receive a guided tour of the space to orientate themselves before being left alone for the night. A staff member remains available above ground for the duration of the stay, contactable by an intercom radio. Guests are also reminded that cell phones do not work this deep underground! 

There is a toilet located 50 meters (165 ft) below ground, however guests will have to use the bathroom facilities in the adjoining hostel above ground.
The mine also features two dining rooms in the vicinity of the hotel suite, where dinner guests can experience a banquet in a truly unique environment.

Above ground, in the southern area of the mine, lie several high wire adventure tracks, including ropeways, hanging bridges and other tree challenges. But if you'd prefer to go underground, adventurers have the opportunity to go cave diving. The cave dive offers a limited number of divers access to explore the mine's underwater environment. The water temperature is constantly a chilly 2 degrees Celsius / 35 degrees Fahrenheit, however divers braving the cold conditions are promised a "spectacular scenery" experience.
A night's stay in the underground suite at the Sala Silvermine will cost approximately US$580.