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 Madagascar (Marosakabe - 113km) and Algeria (Rhar Bou Ma’za - the Tafna River Cave 18.4 km) have overtaken it. It is situated to the east of Ginnir, in the East Bale Zone of the Oromia Region in southeastern Ethiopia, through which the Weyib River (Gestro River) flows. 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".