David Attenborough takes us through the incredible series of active and inactive volcanoes that make up the Galapagos Islands and explains how these dramatic landscapes have created equally dramatic adaptations in the animals who live there. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater.