Leviathan Cave

Lava tube in eastern Kenya
Abstract

Leviathan Cave, also known as the Grotte de Leviathan, is a lava tube in eastern Kenya first discovered in 1975. Although it has been segmented by the movement of tectonic plates, the overall length of the lava tube spans a distance of 11.5 km (7.1 mi). It is the longest and deepest known lava tube in Africa.

Wikipedia