Karst is widespread on the peninsula of Qatar, including depressions, sinkholes,caves, and solution hollows. More than 9700 large and small depressions, and several exposed sinkholes and caves are known, but many have probably been filled with blown sand, or have collapsed to produce some of the thousands of depressions. Many of these depressions are the surface expression of subsurface collapse structures.
Musfer sinkhole has an opening of 12 x 5 m and is at least 100 m deep (the bottom that we can reach at the moment), that filled with sloping loose sand at the bottom. Gypsum layers of the Lower part. It was suspected that this sinkhole is part of a much larger cave system.
Mudlem Sinkhole (Dark Cave) is ~150 m deep, filled with sloping loose sand and brackish water at the bottom. The hole has an opening of 15 m in diameter. When we visited, the entrance had been closed.
It may not easy to find. With GPS, it will help. Set your GPS target for Musfer Sinkhole at 25 10.50'N 51 12.714'E