East of Reykjavik, Iceland lies the mountain, Hengill. Hengill was formed from a Palagomite tuff, it is a central volcano and has a giant magma chamber beneath it. When thick basalt lava flows cool, they form hexagonal cracks, called columnar joints. These can be found also in Ireland & Scotland.
Easily the most photographed site in all of Iceland, The Blue Lagoon is perhaps the most supernatural looking body of water on Earth. The water in the lagoon is anything but frosty. The temperature averages about 104F and the soothing, mineral-rich water is rumored to have curative powers.