Anou Boussouil

Anou Boussouil (in English "Great Chasm") is a limestone karst cave located in the mountains of Djurdjura, Algeria.[1] The cave is 3,200 metres (10,500 ft) long and 805 metres (2,641 ft) deep.[2] The entrance to the cave is 1,074 metres (3,524 ft) up the mountainside.[3] During the springtime rainy season, melting snow pours through a channel leading directly to the cave mouth, continuing the process of erosion.[3] This distinguishes it from other caves in the Djurdjura range, which are inactive and no longer being enlarged through erosion.[4]

The cave was first scientifically explored in 1933 by the cavers Fourastier and André Belin.[3][4] 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 metres (213 ft) into a sequence of pit chambers. Within this sequence is a gallery known locally as salle des affamés, or "the hall of the hungry".[4][5] This segment eventually opens into a flooded vault chamber.[3]

In 1950, it was explored to a depth of 505 metres (1,657 ft); at that time it was known as the second-largest pit in the world.[2] An expedition in 1980 found that the cave reaches a maximum depth of 805 metres (2,641 ft).[2] It was briefly known as Africa's deepest cave before Anou Ifflis was explored to a depth of 1,170 metres (3,840 ft).[2]