Hades

In the small hours, the mist hovering over Mount Nyiragongo's crater clears to reveal the world’s largest lava lake. The volcano, which lies in the Virunga National Park in the North Kivu province of the Democratic Republic of Congo, has erupted 34 times since 1882, often with disastrous effects on the nearby city of Goma. The bubbling lake is 300m in diameter and its heat can be felt at the upper rim, where visitors are rewarded after a six hour slog to the summit; it’s like looking into Hades.