The aquamarine colour of the lake surrounded by red volcanic rock is what makes it so unique. Kerid or Kerið Lake is located in the Grímsnes area in South Iceland. The area boasts several crater lakes in the area, which is called Iceland's Western Volcanic Zone. The caldera, 55 m (180 ft) deep and 170 m (560 ft) wide, is composed of a rare red volcanic rock. Kerid's caldera is approximately 3,000 years old, which is relatively young in comparison to other volcanic formations in the area.
One wall of the crater is covered with moss, so one can descend relatively easily. The lake itself is quite shallow (7–14 m), and boasts surreal blue water due to its high mineral content.
The Kerid volcano could have formed when the magma exhausted itself, creating an empty chamber beneath. The lake is usually visited along tours of the Golden Circle. It's located 15 km north of Selfoss.
The nicest time to visit is from May through October. In summer the area is the most scenic with blue water, red volcanic walls, and green moss. While in winter the lake freezes and the ground is covered with snow.