Seljavallalaug is one of Icelands oldest swimming pools, built in 1923 to teach people how to swim. it is situated in a gorgeous mountain valley surrounded by multiple small waterfalls and a roaring river just off to the side of the pool. The hike to the pool takes about 10 minutes. The temperature of the pool can vary day by day but seems to be trending colder over the years, most days now it's usually luke warm.