While Iceland is famous for its hot springs, native Icelanders visit geothermal pools much more frequently. Reykjavik has several but Laugardalslaug is the largest and most prominent.
Laugardalslaug is just a short bus ride or walk from downtown and we visited our first morning in Iceland.
If you're anything like me, life in the good old USA has made you very wary of public pools and waterparks. No worries. Laugardalslaug is very well kept. After you enter and change there's three Olympic sized swimming pools, all geothermally heated to chose from: two outside and one indoors. There's also a sauna, steambath, and selection of "hot pots", small hot tubs in varying degrees of heat that did wonders for my Reykjavik induced hangover.
I was floored by how many people were just hanging out at the pool and hotpots and sunbathing (it was around 60, which is warm for Iceland) and how this was a normal thing or way to relax. I wouldn't hate if it caught on stateside (granted they keep up with Iceland's superb sanitation).