Reykjadalur is a valley above the town Hveragerði and a 90 minute long marked hiking trail leads up the green valley to the warm river Reykjadalsá in Klambragil. The trail begins at the mouth of Reykjadalur valley, where there is a great view of the Djúpagil gorge and its inspiring waterfall. The trail then leads up Reykjadalur and across a lukewarm but shallow river, where wading is required. A bit further up you will reach Klambragil, a ravine where hot streams flow into the Reykjadalsá river, creating an ideal temperature for a relaxed bath, including some natural jacuzzis. Note that the hot streams themselves are too hot for bathing. There are numerous onward hiking possibilities from Klambragil and there is an amazing gorge nearby with several hot springs and a beautiful little waterfall at the very end.