Crater Lake is a caldera lake in the Crater Lake National Park (Oregon, USA). It's known for water clarity and a deep blue color. Crater Lake partly fills a 1.2km deep caldera which was formed ages ago by the collapse of the Mount Mazama volcano.
5 most visited places in the world. Why millions of people are visiting these places?
Gibraltar, an island situated off the southern coast of Spain, has an entire network of limestone caves just waiting to be investigated. Find out more about this fascinating geological spectacle.