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
Dettifoss Waterfall, Iceland: Would NOT recommend going this close to the edge. People have fallen into icelandic waterfalls before, doing exactly this, and not survived.
Svartifoss, Iceland Photograph by Giacomo Ciangottini Svartifoss (Black Fall) is surrounded by the dark lava columns that gave rise to its name. The hexagonal columns were formed inside a lava flow.