The Blue Lagoon is one of Iceland’s most famous spots. With warm milky-blue water at around 37–39°C and dark rocks, this spot is perfect for relaxing. It’s more of a luxury spa than a wild hot spring, so expect crowds during high season and higher prices. Still it’s worth visiting at least once, especially if you go early in the day. They also give you a face mask (the silica mud mask leaves your skin feeling incredible).