You’d think that the last place on Earth people would want to inhabit would be the bottom of a steep volcano hosting the world’s largest fluid lava lake. Despite the constant threat of catastrophic fiery death, the area at the foot of Mount Nyiragongo is dotted with highly populated bustling villages.

One such disaster occurred in 1977, when the walls of the crater burst open and the lake of molten rock drained in less than an hour, pouring itself down into the villages at a terrifying speed of up to 60 mph. Unlike your average lava flow, the unique presence of an alkali-rich volcanic rock, melilite nephelinite, creates a highly fluid consistency, allowing it to move at speeds that can easily overcome anything in its path. The official death toll was 70, but many report much higher numbers, some estimating the losses at several thousand.

The 1977 eruption took place when the lake was at its maximum depth ever recorded, 10,700 ft., but the extent of its volume varies depending on activity. No one knows how long the volcano has been active, but since 1882 it’s been very busy, erupting at least 34 times, occasionally bubbling and spewing fire for years before settling down.

Located inside Virunga National Park about 20 km. North of Goma, Mount Nyiragongo is currently still active, its last deadly eruption taking 147 lives in 2002. Its activity is, for now, being confined to the crater, where the lake of lava is slowly rising once more.