Grjótagjá is a small and secluded lava cave and hot pool located near Lake Mývatn in the northeastern region of Iceland. To get there, travel on Route N1, the “Ring Road,” and turn south on Route 860 which is along the eastern shore of the lake. There will be a small sign and road on your left that leads to a gravel carpark in front of the cave. From here you can see an information sign and two entrances leading inside. It is free and open to the public for inspection and photography. Enter at your own risk, and be aware that rocks are capable of falling or collapsing from the roof of the cave. Swimming is prohibited!
Sometimes this site becomes very popular and there are lines at the opening. There are no ladders or assistance implements, so watch your step as you descend down the large rocks a few meters to the water’s edge. You can hop across a few rocks to get farther into the cave. The clear water creates a deep and majestic scene. During the summer, daylight creeps in to create a wonderful blue and gold reflection of the rocks above. You may even see steam rolling across the surface if the temperature and humidity are just right. This land is privately owned by the Vogar Farm, and you are not allowed to bathe. Please respect this rule and note that the water may be extremely hot!
This hot pool was a popular for bathing until the 1970s, but it fell out of use as volcanic eruptions at Krafla between 1975 and 1984 caused a surge in the water temperature to 60°C (140°F). Since then, the water temperature has been slowly dropping, and today it is in the range of 43° to 46°C (109° to 114°C).
Outlaw Jon Markusson is said to have lived here in the early 18th century. More recently, fans of the popular HBO series “Game of Thrones” will recognize Grjótagjá as the film location for the love scene between John Snow and Ygrette in season 3, episode 5. (An additional CGI waterfall was added in the background.)
While you are not allowed to enjoy the warm water here, there is another nearby lava cave with a hot pool called Stóragjá where you can go. The Lake Mývatn area is part of the “Diamond Circle” and hosts a number of incredible attractions and points of interest such as Hverir geothermal site with its hot mud pits and fumaroles, Dimmuborgir with is extraordinary maze of natural lava sculptures, Höfði Nature Park with its numerous species of waterfowl, and Jarbodin (Mývatn Nature Baths) with its naturally heated water.