Anou Boussouil

Anou Boussouil (in English "Great Chasm") is a limestone karst cave located in the mountains of Djurdjura, Algeria. The cave is 3200 m long and 805 m deep. The entrance to the cave is 1074 m up the mountainside. During the springtime rainy season, melting snow pours through a channel leading directly to the cave mouth, continuing the process of erosion. This distinguishes it from other caves in the Djurdjura range, which are inactive and no longer being enlarged through erosion.

The cave was first scientifically explored in 1933 by the cavers Fourastier and André Belin. Later expeditions found that the cave was actually composed of two separate segments. The first segment is twisted and relatively narrow, eventually opening up into a larger cavern. The entrance to the second segment is a sinkhole descending approximately 65 m into a sequence of pit chambers. Within this sequence is a gallery known locally as salle des affamés, or "the hall of the hungry". This segment eventually opens into a flooded vault chamber.

In 1950, it was explored to a depth of 505 m; at that time it was known as the second-largest pit in the world. An expedition in 1980 found that the cave reaches a maximum depth of 805 m. It was briefly known as Africa's deepest cave before Anou Ifflis was explored to a depth of 1170 m.