The Secret Lagoon is a kind of literally secret, although it's located just a hundred kilometres west of the well-known Blue Lagoon, deeper into the mainland, in Flúðir. In fact, it's one of the oldest of all geothermal pools found in Iceland. Recently it has been renovated with all modern facilities.
It's open all year round, with just slightly longer operating hours in the summertime (May–September). Nevertheless, we recommend the off-season, as it's more convenient to enjoy the baths in the dead of winter with no crowds.