Hawiyyat Najm (Arabic: هوية نجم), known as Bimmah Sinkhole in English, is a water-filled depression, structurally a sinkhole, in the limestone of eastern Muscat Governorate in the Sultanate of Oman, very close to the Al Sharqiyah region just off the highway to Sur, few kilometers before Tiwi.
[1] A lake of turquoise waters, it is 50 m by 70 m wide and approximately 20 m deep.
It is only about 600 m away from the sea, between the coastal towns of Ḑibāb and Bamah (Bimmah).
The sinkhole was formed by a collapse of the surface layer due to dissolution of the underlying limestone.
[2] However, locals used to believe this sinkhole in the shape of a water well was created by a meteorite,[3][4] hence the Arabic name Hawiyyat Najm which means "the deep well of the (falling) star".