Hengill, Iceland - 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
Best Hot Springs Around the World that are Earth’s Greatest Gift to Mankind Blue Lagoon, Iceland, a geothermal spa. The outdoor bath remains year round. The natural ingredients of the warm water: mineral salts, white silica, and blue green algae
Ice Cave In Bayfield, Wisconsin's Apostle Island's National Lakeshore Park!