Lava Cauldron, Democratic Republic of the Congo

Photograph by Carsten Peter , National Geographic

Exhaling clouds of gas, a cauldron of lava boils in the mile-wide crater of Nyiragongo, an active volcano in the Congo that threatens two million people. Eruptions have blistered the region for millions of years, since the African tectonic plate began to split apart to create the Albertine Rift.