A
lava lake at
Mount Nyiragongo, a volcano found in
Virunga National Park in the Democratic Republic of the Congo. Lava lakes, which can form in three different ways, are large volumes of molten
lava, usually
basaltic, contained in a volcanic vent, crater, or broad depression. Persistent lava lakes such as the one at Nyiragongo, which is the largest to appear in recent times, are rare.
Photograph: Cai Tjeenk Willink