The Sof-Omar Cave

Sof Omar Caves is the longest cave in Ethiopia at 15.1 kilometres (9.4 mi) long. When surveyed in 1972, it was the longest cave in Africa. Since then explorations in Algeria (Rhar Bou Ma’za - the Tafna River Cave 18.4 km) and Madagascar (Ambatoharanana - Crocodile Cave 18.1 km) have overtaken it. ^[1] It is situated to the east of Robe, in the Bale Zone of the Oromia Region in southeastern Ethiopia, through which the Weyib River (Gestro River) flows.^[2] It sinks at the Ayiew Maco entrance and reappears at the Holuca resurgence 1 kilometre (0.62 mi) away. According to tradition Sof Omar was the name of a Muslim holy man who lived in the area and Ayiew the name of his daughter. Maco and Holuca are local names for 'name' and "cave", respectively. Long a religious centre, it is sacred both to Islam and the local Oromo traditional religion. The caves are known for their many pillars, particularly in the "Chamber of Columns".

The cave is formed along a network of joints: one set runs approximately north to south and the other east to west. This zig-zag of passages runs in an approximately southeasterly direction. Sof Omar has 42 entrances, but generally only four are useful for gaining entrance:

• Two upstream Village Entrances (one to the east and one to the west of the village)
• The Tourist Entrance downstream from the Holuca Resurgence at a point where the abandoned meander forming the dry valley rejoins the Web river
• A right bank entrance downstream of Holuca accessing the Deep South part of the Clapham's Climb Series.

Entering the cave via either of the Village Entrances the visitor passes a shrine used by the locals. The Ayiew Maco Series is a set of interconnecting passages of varying in width between 1 m and 10 m. Several can be passed through to the pebble beach on the left bank of the river. A less complex series of passages exists on the right bank.