An energizing hike. A snow-covered volcano. Plus the sky brightening with the late-rising sun. This morning can’t possibly get any better. Or can it? Add waterfalls, fumaroles, and even a hot spring. That’s right. The trail leads to a thermal pool. It’s time to strip down, quickly jump in the water, and go for a soak.

In Iceland, people have been bathing in volcanically heated pools for, well, ever. The Vikings did it. Icelanders continue the tradition today. Even tourists have caught on. The Blue Lagoon is one of the most visited sites in the country. Reykjavík is full of public pools. While remote hot springs keep popping up on your Instagram feed. There are more than 700 geothermal areas to explore in this small country. You’re starting at Reykjadalur.

It was only a 40-minute drive outside of Reykjavík to begin today’s adventure. It was still dark when you left, but by the time you reached Hveragerði, grays and purples had overtaken the pitch black overhead. Hveragerði is known as the Gateway to South Iceland. Upon first glance, the small town along Route 1 just looks like a good place to stop for gas. But once you drive by the boxy buildings, you find the remains of a 20th-century wool mill, geothermally heated greenhouses, and, in the distance, Hengill. Hengill is a volcano that last erupted about 2,000 years ago. The fumaroles and the hot springs in the surrounding Reykjadalur Valley prove that it’s still active, though.

The road ends at the Hot River Cafe. Though the cafe is closed much of the year, there are usually cars in its parking lot, since it sits near the head of the Reykjadalur Hot Spring River Trail. At about 2.5 miles roundtrip, the first—and the most popular—section of the trail is short and, for the most part, wide. That doesn’t mean that it’s easy. The trail ascends from a steady incline to a steep slope. In front of you, steam spurts from small crevasses, holes are filled with bubbling mud, and “hætta” signs warn of dangerous areas. At one point, you have to choose between clinging to the side of an icy cliff or sliding down a steep hill on your butt. The steep hill wins. The whole time, the snow-covered valley, Hveragerði, and the fierce Atlantic Ocean are behind you. While the strong scent of sulfur is everywhere.

After about an hour of hiking, the trail descends into another valley. Wooden docks and semi-private changing stalls line the river in the middle of it. Modesty goes out the window with the wind chill. You pull off your winter boots and thick layers (but keep your hat) and quickly pull on your bathing suit, as your fingers start to feel numb. You slide across the icy boardwalk. Then you slip into the warm water. Though you’re surrounded by snow and ice, the cold has disappeared.

The worst part of the day, by far, is eventually getting out. It takes a few tries for you to force yourself out of the water, up the steps, and back to your backpack. You rush to towel off, redress, and start moving as fast as possible. Since it’s mostly downhill, the return hike feels quick and easy. Plus there’s a treat waiting on the windshield of your rental car. It’s a flyer from Ölverk, a new brewery and pizzeria in the center of town. A carb-filled lunch of cheesy bread and wood-fired pizza, plus a tasting of geothermally brewed beers, sounds amazing right now. The combination is sure to take the rest of the chill out of you. Skál!