Secret Lagoon & Kerið Crater★★
Secret Lagoon (Gamla Laugin)
The Secret Lagoon in Flúðir is Iceland's oldest thermal bath (built in 1891, reopened in 2014) and a wonderful alternative to the crowded Blue Lagoon. The natural pool (25 meters long) is fed by hot springs (38–40°C) and lies amidst steaming fields with a small geyser (Litli Geysir) that splashes every few minutes.
The atmosphere is more relaxed and authentic than in the Blue Lagoon: Wooden walkways lead around the natural pool, steam rises into the air, and in winter, you can watch northern lights over the warm water with a bit of luck. The water is not milky like in the Blue Lagoon but clear and slightly greenish — it contains natural minerals and silica.
Admission: 3,500 ISK (23€) — significantly cheaper than the Blue Lagoon. Perfect stop on the way back from the Golden Circle. Towels can be rented on-site (1,000 ISK).
Laugarvatn Fontana
Between Þingvellir and Geysir lies Laugarvatn Fontana — a modern geothermal spa on the shores of Lake Laugarvatn. The special feature: You can switch between the hot mineral baths and the natural lake (the lake has refreshing 10–15°C in summer). A steam cave (natural steam from the Earth's interior) and a demonstration of traditional Rúgbrauð baking (rye bread baked for 24 hours in the hot ground) are unique.
Kerið Crater
The Kerið is a roughly 3,000-year-old volcanic crater filled with a bright turquoise lake. The crater rings of red and black volcanic rock form a dramatic contrast to the aquamarine water — especially in sunlight. The crater is 55 meters deep, 270 meters wide, and 170 meters long.
Geologically, Kerið is unusual: Most volcanic craters are formed by explosions, but Kerið collapsed inward when the magma chamber emptied — similar to a crushed drink can. The water level in the crater fluctuates with the groundwater level, not with the rain.
A circular path (15 min, 900 meters) leads around the crater rim and offers views from different angles. A steep staircase leads down to the lake — down there, you stand amidst the red-black crater walls and look at the turquoise water. Occasionally, concerts are held in the crater in summer — the acoustics are exceptional.
Kerið is located directly on road 35, only 15 km north of Selfoss — an easy stop on the way back from the Golden Circle to Reykjavík.
💡 Tipp
Visit Kerið in the late afternoon — then the sun is low and illuminates the red crater walls particularly dramatically. On cloudy days, the turquoise of the lake is less intense. The Secret Lagoon is most atmospheric in the evening — fewer visitors, steam in the dark, and in winter, northern lights over the warm water.
