Krosslaug is a natural geothermal pool about the size of a large hot tub, comfortably fitting 4-6 people, so it isn’t very large. Below this pool, there is another one of a similar size, but with cooler water.
You can find this pool near road number 52. After parking at the designated area (GPS: 64.504125, -21.203828), go through the metal gate and follow a pleasant path through a small forest for about 100 meters to reach the pool.