طوي أعتير

Tawi Ateer - Birds Well

Useful Information

Location:	Between Mirbat and Salalah, north of the coast, Qara Mountains, Governorate of Dhofar. (17.1136152, 54.5593713)
Open:	No restrictions. [2023]
Fee:	free. [2023]
Classification:	Doline
Light:	n/a
Dimension:	VR=210 m, A=680 m asl. Entrance: 130x90 m.
Guided tours:	self guided
Photography:	allowed
Accessibility:	no
Bibliography:	Mohamed Alian (2010): The largest sinkhole in Oman, Observer Weekend, Wednesday 21 April 2010. G. Crouch (2003): Caves of Oman, National Geographic, April 2003 issue. online S. Hanna, M. Al Belushi (1996): Introduction to the Caves of Oman, Sultan Qaboos University, International Printing Press, Ruwi, Sultanate of Oman.
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History

1980	cave fish discovered by British cavers.
1997	explored by Slovenian cave explorers and members of Sultan Qaboos University.
2003	featured by National Geographic.

Description

طوي أعتير (Tawi Ateer), also known as بئر الطيور (bir altuyur, Bird Well) is only one possible transliteration of the Arabic word, others are Tawi Atayr, Tawi Atir, Tawi Atair, and Tawi Attair. The Niyabat (administrative unit) Tawi Ateer covers an area with 116 villages. The administrative center is located 900 m south of the sinkhole, and is also called Tawi Ateer. There seems to be some confusion which was named after which and what the name means. The standard explanation is, the sinkhole was named Tawi Ateer, which translates Well of the Birds, because of the numerous birds living in the cave walls. It seems undisputed that tawi is the Omani word for well, but ateer is not the word for bird. The water from the well was the basis of a cow herder settlement named Ateer and the well was thus named Tawi Ateer (Well of Ateer village). The locals actually call it Alsharkh, which literally means fissure. We do not know which version is true.

Tawi Ateer Sinkhole is a 210 m deep daylight shaft, the entrance to a vast cave. The opening at the surface is of oval shape, the main axis is northeast to southwest, with a length of 130 m and a width of 90 m. At a depth of about 100 m the shaft narrows, and is only 60 m in diameter and almost circular.

The sinkhole can be found northeast of the Tawi Atayr Administrative centre. It is badly signposted but there is a new parking lot and a new trail with a viewing platform. For a better view, take a walk around the hole, which takes about 20 minutes. Be careful at the rim, it is really deep! As far as we know, it is possible to climb down halfway into the sinkhole, you can simply walk down the wadi. Where the shaft narrows and the walls become vertical, there is an iron platform that was once used for pumping water. From here it's definitely the domain of the cavers.

There is a long wadi, ending at the sinkhole, which actually makes it a river sink. The wadi transports enormous amounts of water into the cave during one of the rare but heavy rains. The entrance is located in the mountains, about 680 m asl. The sea is only 10 km to the south, so the potential is a cave system of almost 600 m vertical range.

Looking at the geography, the cave might either drain directly to the sea with underwater springs or to nearby Wadi Dharbat (also Wadi Dirbat). Here the limestone rich karst water reappears and forms waterfalls, which are actually rimstone pool, formed by the deposition of limestone in form of tufa, building dams.

The whole Qara plateau is karstified, there is a vast system of caves, mostly filled with water. The water level of the groundwater is actually very high, only 210 m below the surface, which is where caving ends and also limits the depth of this cave. In 1980, a team of British cavers visited the water level at the ground of the shaft. They discovered the Biology troglobite Garra dunseiri, named after Arthur Dunsire, the collector. The fish is endemic, depigmented, but still has eyes.

Some descriptions on the web explain the formation of the sinkhole with the collapse of a huge cavern or chamber. This is actually very unlikely. Such entrance shafts form from the widening of cracks and clefts in the rock by solution and erosion. There is an enormous change of temperature between day and night. This continually destroys the rock. If it freezes, the water in the cracks freezes too, expands and destroys the rock. The upper half of the shaft is heavily influenced by surface weathering and the erosion of the wadi. The shaft becomes steep where the influence of the surface ends, and only the solution of water flowing down the walls widens the shaft. So there has never been a big collapse, just a slow, continual process of widening.

The shaft is also named Well of Birds”, because it is a preferred spot for migrating birds. The reason is simply the lake at the bottom, the birds fly into the shaft for drinking. There are different species of bird, most birds are here during the Khareef Season, the wet or monsoon season.