Bimmah Sink Hole

Hawiyyat Najm — widely known as the Bimmah Sinkhole — is a natural doline punched into a wave-cut platform of Eocene limestone on Oman's northeastern coast. The oval pool is roughly 40 metres across, with the rim sitting about 20 metres above the water surface. The sinkhole formed through classic karst dissolution: seawater gradually ate through porous limestone over millennia until the ceiling collapsed, creating a basin fed by both fresh groundwater and seawater intrusion, giving it a distinctive brackish character. Concrete steps lead visitors down the rock face to a turquoise pool where swimming and snorkelling are possible. The sheer walls, clear water, and proximity to the Gulf of Oman make it one of the more otherworldly natural bathing spots on the Arabian Peninsula.