Trou au Natron

The Trou au Natron is a caldera in the Tibesti six to eight kilometres across and up to a kilometre deep, and its floor is covered in a crust of white natron, a sodium carbonate deposit left by a lake that dried, so that looking down into it from the rim gives a white plain with several small black cinder cones standing on it. Fumaroles still vent at the bottom. The descent to the floor takes several hours.

The landscape

• The white floor - the natron crust left by an evaporated lake.
• The cinder cones - the small black cones standing on the caldera floor.
• The scale - a crater six to eight kilometres across and up to a kilometre deep.
• The fumaroles - the vents still active at the bottom.

When to go

November to February is the cool season and the practical window. March to May is extremely hot. The descent should start early.

What to expect

The descent to the floor is long, steep and unmarked, and the climb back is worse. Access requires a full expedition with permits and guides. There is no infrastructure or rescue.

Nearby

Bardaï is north, and Emi Koussi is south.

Key facts