Majlis al Jinn

Hidden beneath the Selma Plateau in Oman, roughly 100 kilometers southeast of Muscat, Majlis al Jinn is one of the largest known underground chambers on Earth, its floor covering enough area to park several jumbo jets. Local Bedouin communities named it the "Meeting Place of the Jinn" long before its existence was confirmed to outsiders, believing the vast, echoing sinkhole — accessible only by rope descent through a narrow opening in the desert floor — was where the jinn of Islamic tradition gathered beyond human sight. American caver Don Davison is usually credited with the cave's first documented Western exploration in 1983, though local shepherds had long known of the pit and avoided its rim, wary of livestock — and reportedly themselves — being pulled toward the opening by the wind that howls up from below. Today it remains accessible only to permitted, experienced cavers rappelling roughly 150 meters into darkness.