Ice cave in the Skaftafell National Park in Iceland. Ice caves collapse and new ones form as each glacier grinds slowly towards the sea. Local guides can help you (without dying) find one. (Visit Skaftafell National Park in Iceland.
East of Reykjavik lies a mountain named Hengill. Hengill was formed from a Palagomite tuff and its highest point is around 800 metres above sea level. Hengill is a central volcano and has a giant magma chamber beneath it.