Secret Lagoon

Secret Lagoon, known locally as Gamla Laugin, sits in the geothermal field of Hverahólmi near Flúðir on Iceland's Southern Peninsula. The pool dates to 1891, making it the oldest swimming pool in the country, and it reopened in its current form in 2014 after years of disuse. Water comes entirely from three sources on site — Vaðmálahver, Básahver, and the small active geyser Litli Geysir, which erupts every few minutes in view of bathers. The pool refreshes completely every 24 hours and holds steady at 38–40°C year-round, with a noticeably sulfurous smell from the mineral-rich water.

A walking path circles the lagoon and geothermal area, letting visitors watch the boiling springs and the geyser up close without stepping into hot ground. Facilities are simple: showers and a bistro on site, plus swimsuit and towel rental for those who turn up without gear. The site is open to walk-ins and offers day passes, and there are no gender-specific hour restrictions or clothing-optional sections — this is a standard swimsuit-required pool, welcoming families.

The spa operates daily from 10:00 to 20:00. Pre-booking is encouraged since spots aren't guaranteed without a reservation, particularly in high season. Staff and signage are available in both Icelandic and English, and pricing sits at the lower end of the scale compared with Iceland's bigger geothermal attractions.