Reykjadalur free translated, the steam valley, is one of the easiest hot spring areas to reach from Reykjavík.
You will find the hot spring only 45 minutes’ drive from Reykjavik in the town of Hveragerði.
From there you can hike up to the warm river that flows down Reykjadalur. There are no facilities for changing your clothes when you get up there.
Find routes to this destination.