Thanks to two tectonic plates that run from southwest to northeast (the Eurasian Plate and the North American Plate), Iceland contains a plethora of geothermal pools, streams, and lagoons with each town featuring its own naturally heated warm water gathering place known as a sundlaug. A stone’s throw from downtown Reykjavík, Sky Lagoon reimagines and elevates the notion of a sundlaug.

Housed in a series of buildings that incorporate living walls and blackened timber, the project merges Norse bathing culture, sustainable design, and nature. Although the 230-foot, infinity-edge geothermal pool is manmade, complete with a swim-up bar and carved volcanic rock submerged seating areas, the uninterrupted views of the North Atlantic (and, on a clear night, the Northern Lights) cement guests in an autochthonous environment.

Stepping from a well-appointed changing area via a cave-like tunnel directly into the hot water eliminates the shock of transitioning from indoor to outdoor. Jagged lava formations and lush hillsides rise like the steam above the undulating surface. Mimicking a fjord, the pool incorporates rocks rising up from its depths as well as a warm waterfall.

Deep, restorative benefits come from the Sky Ritual, a seven-step process developed over centuries. Departing the large pool, the first round of cold arrives via the crisp Icelandic air and a circular, stone-lined cold pool for a polar plunge. It’s a nod to the historic Snorralaug pool in the north, dating to the 13th century. A one- to three-minute plunge constricts and then increases blood flow, strengthens the immune system, and tightens the skin. Iceland’s first settlers built homes by cutting and stacking turf, thus the Sky Lagoon used the method for its own turf house, which holds a vast, light-filled, oceanfront sauna. Take in views through the largest single pane of glass in Iceland (weighing in at 5,000 pounds), while the heat blast opens pores and flushes out toxins.

After five to 10 minutes, move to the turf house’s rain-simulated, open-air room for step four, the cold mist. Step five takes place inside a steam room where spa-goers exfoliate with Sky Body Scrub, made of coarse sea salt flakes, sesame oil, and coconut served in individual wooden askur bowls (just like the Vikings used in their antediluvian turf houses). Marinate in the steam for 15 minutes then finish the ritual with a warm shower to rinse away the scrub and any remaining stresses and aches.

Post-aquatic therapy, linger at the Smakk Bar or Sky Café, which serves soups, sandwiches, and locally sourced plates that include traditional favorites like gravlax (dry-cured salmon) and reindeer. skylagoon.com