#arrivalguide I left Reykjavík at 4 pm and reached the Hveragerði trailhead car in 40 minutes via Route 1. The Reykjadalur ("Steam Valley") hike is the most accessible wild geothermal soak near the capital, but people underestimate it. The signed trail is 3 km one way, about 50–90 min up depending on pace, with ~ sections in the first 800 m where the boardwalk gives way to gravel and mud. I wore trail runners and regretted it—by the upper valley the path was slick with clay and melting snow even in late July. Total river itself sits at 36–40°C where hot runoff mixes with the cold mountain stream; the sweet spot is just above the small wooden bridge where you can rearrange stones to balance hot and cold flow. There's a changing platform, not cubicles—wear your swimsuit under layers, bring a quick-dry towel, and pack out everything. No fee, no booking, open is free but fills by 11 am in summer; evening (after 5 pm) gives you steam-on-water light and fewer people. Hveragerði town has a bakery and a geothermal park if you want a bread-stop before driving back. Rules: stay on the boardwalk sections to protect moss, don't soap the river, leash dogs. A mistake I made once was going midday in August—the valley smelled amazing but the river was crowded with 30 bathers; the second time at 6:30 pm I had a 40 m stretch to myself. Question for others: do you treat Reykjadalur as a workout-plus-soak, or purely a bathing walk where slow is better?