Location: The old Seljavellir swimming pool is located inland from the Seljavellir farm, at the head of the valley. Access: The swimming pool is reached by a walk from Seljavellir. The route is easy and the surroundings beautiful. At the bottom end of the valley, the amazing Seljavallalaug geothermal pool was built in 1923, making it the oldest in Iceland; and it was its largest until 1936. It is now partially filled in with the ash of the 2010 eruption of Eyjafjallajökull but the scenery is fantastic and the water naturally nice and warm.