Þríhnúkagígur

thumb|300px|Inside the magma chamber

Þríhnúkagígur (, anglicized as Thrihnukagigur, literally translated as Three Peaks Crater) is a dormant volcano in the volcanic system of Brennisteinsfjöll near Reykjavík, Iceland. Covering a area and a depth of , it has not erupted in the past 4000 years. It was discovered in 1974 by cave explorer Árni B. Stefánsson, and opened for tourism in 2012. It is the only volcano in the world where visitors can take an elevator and safely descend into the magma chamber. The magma that filled the chamber has drained away, revealing the void beneath the surface.