Located within the vicinity of the quaint town of Hveragerði, just 45 kilometers away from Iceland’s capital, Reykjavik, this smoke-shrouded, hidden valley is a part of one of the largest geothermal areas in the country.

A popular local hiking trail leads into the valley after about an hour’s trek, which is eventually dominated by a gorgeous geothermal river. The river bank is reminiscent of a muddy expressionist painting due to the natural composition of the waters. Near boiling waters from a natural hot spring mix with cold river waters in the valley, creating hot baths that visitors can relax in. Many locals and visitors actually come here to bathe in the warm river but keep in mind there are no bathroom facilities so you’ll have to strip in the cool Icelandic air.

Also, pay heed to the signs warning “Hætta!” (this means “Danger!” in Icelandic). Along the gravel path leading into the valley, not only will you see beautiful sights of waterfalls, but you’ll also find hot, bubbling (and yet beautiful) mud pools that reach temperatures of 100ºC. The steam rising from these pools pours over the hiking trail like a warm sulfur-smelling fog. Signs remind hikers to stay on the trail because flowing under the ground is hot, molten lava and you never know when a hot spring might erupt in your face.

The town of Hveragerði is actually powered in part by the same geothermal energy that makes Reykjadalur such a haunting location.