Colinas de Chyulu

Declared in 1983, the Chyulu Hills are one of the youngest volcanic ranges in Africa, thrown up by eruptions barely 500 years ago — so recent in geological terms that the volcanic rock has yet to develop any significant cover of fertile soil. Beneath the hills runs Leviathan Cave, one of the longest lava tubes in the world, formed as a lava flow cooled on the outside while the inside kept running, leaving a tunnel several kilometres long.