Seljavallalaug hot spring pool in Iceland/Seljavallalaug, Iceland/Seljavallalaug is a unique geothermal hot spring pool located in a small valley at the foot of the Eyjafjallajökull glacier near the Seljavellir.It was built in 1923 and is one of the oldest swimming pools in Iceland. The initiator of the construction of this facility was Bjorn Andresson. It was originally made of stone and one of the walls of the pool is a mountainside. Seljavallalaug measures nearly 25 meters long and 10 meters wide, being the longest pool in Iceland up until 1936.It was here in 1927 introduced compulsory swimming lessons. It was once the skills necessary for people living from fishing. Interestingly, in Iceland, one of the obligatory Matura exam is the exam of swimming.Seljavallalaug is filled with pure spring water, flowing from the Eyjafjallajökull volcano. Heat is, of course, in a place where water is supplied thereto even hot.