Majlis al Jinn

Under the Selma Plateau in Oman, about 100 kilometres south-east of Muscat, lies one of the largest underground rooms on Earth: a single domed chamber 120 metres high with a floor of 58,000 square metres, reachable only by rope through three shafts that pierce a roof some 40 metres thick. Its Arabic name, مجلس الجن, means the meeting place of the jinn — and the story usually told about that name is the wrong way round. It was not handed down by Bedouin before outsiders arrived. The American hydrogeologist W. Don Davison Jr., who spotted two full-stop-sized dots on a 1982 aerial photograph and made the first descent alone on 23 June 1983, wrote that he and his wife, the caver Cheryl S. Jones, gave the cavern its name only after finishing their survey in 1985. Jones was first down the narrowest shaft, a 158-metre free fall that still carries her name. Local people called these holes khoshilat, and the plateau kept a different legend: that stars were cast from the heavens to form seven of them, in memory of a woman named Selma.

Majlis al Jinn is a single limestone room under the Selma Plateau, in Oman's Ash Sharqiyah South governorate, about 100 kilometres south-east of Muscat. It has no walk-in entrance. The only ways in are three vertical shafts that pierce a roof roughly 40 metres thick and open, without warning, into a domed chamber some 300 metres across and 120 metres high. The man who found it was not an adventurer but a civil servant. W. Don Davison Jr., an American hydrogeologist, arrived in Oman in September 1980 to work in the Karst Research Program of the Sultanate's Public Authority for Water Resources (PAWR). The programme's purpose was practical and unromantic: to work out how water moves through limestone country, because in an arid nation that is a question of national supply. Davison began looking for large caves as part of the job. For two years the search produced almost nothing. Then, in 1982, he pulled an aerial photograph of the Bani Jabir mountains and saw a karstic plateau standing out among some of the most broken and inaccessible terrain in Oman. What caught his eye were several large swallow-holes — and, at the northern edge, two black dots each about the size of a full stop. As he later wrote, they "gave no clue, even under magnification, to the scale of the discovery hidden in their featureless depths." In January 1983 Davison and his wife, the caver Cheryl S. Jones, reached the plateau after a strenuous six-hour hike from the coast, passing the small herding camp of Sukun on the way up. They ran out of time and turned back without finding a single one of the features on the photograph. He returned in June 1983, this time by air: an adventure training instructor named Doug Green arranged seats on an Omani air force helicopter working in the area. Dropped in the middle of the plateau, the two men walked a compass line north across thorn scrub and rubble and located five cave entrances in one day. Two of them were the dots. They measured each drop with a small weight and a spool of fine copper wire: one about 120 metres, the other 140. On the morning of 23 June 1983 Davison went back alone, with four hours until the helicopter returned. He rigged a rope to a large rock at the lip of the overhung pit and went over the edge. "A short distance down, the shaft opened out," he wrote, "and as I dropped lower, turning slowly in midair on the rope, a stupendous panorama was revealed." Five minutes later he landed on a cone of collapse debris beside the skeleton of a large snake and a brightly coloured cloth bundle someone had thrown in from the surface. What he walked across over the next few hours is worth recording, because it is the actual content of the place. A dry lake bed of mud-cracked polygons, 200 metres by 50, that floods only in storms. Stream channels whose gravel is mixed with the bones of animals that had come down the shafts rather faster than he had. Thousands of white cave pearls, some four centimetres across, lying loose in dry pools. A forest of metre-high stalagmites fringed with erratic mineral growths that the surveyors nicknamed "Friar Tuck". Eyeless, translucent cave-adapted pill bugs under a piece of rotting wood. A constant 17–18 °C. Occasional cracks of rockfall echoing across the room. And a slow, disorienting failure of scale: Davison wrote that his sense of distance "could not immediately accommodate such huge distances being under a roof." From the floor he glimpsed a hint of daylight high on the wall — a third, much narrower opening. Cheryl Jones made its first descent in March 1984. At 158 metres it is the longest free-fall drop in Arabia, and it carries her name: Cheryl's Drop. The chamber's status was not established until Davison and Jones completed their mapping survey over five trips in April and May 1985, work written up in the government report PAWR 85-20 in October of that year. The survey gave a floor area of 58,000 square metres and a volume of over four million cubic metres, and made it, at the time, the second largest known cave room on Earth after Sarawak Chamber in Malaysia. Later surveys elsewhere — notably the 2013 laser measurement of the Miao Room in Guizhou, China — have since expanded the table, and it now sits inside the top ten rather than at number two. And it was only at that point, in 1985, that the cave got the name the world now knows it by. Davison is explicit about it: "it was only then that we gave the cavern its name."

Be clear about this before planning anything: Majlis al Jinn is not a show cave, and as of the most recent published check it is still not open to visitors. In 2008 Oman's Ministry of Tourism announced a plan to develop it, and the cave was closed pending that work. Students at the University of Innsbruck drew up a management plan the same year. Nothing was ever built and no formal reversal was ever published; the project was quietly dropped. There is no lift, no tunnel, no stairway, no via ferrata and no zipline. Any operator implying otherwise is selling something that does not exist. Where it is. The Selma (Salma) Plateau, Ash Sharqiyah South governorate, at roughly 1,380–1,400 metres, about 100 kilometres south-east of Muscat, at approximately 22°52′50″N 59°06′19″E. How you would get in. Only by rope. The chamber has three free-fall shafts through a roof about 40 metres thick: First Drop / Khoshilat Maqandeli, 118 m — the widest, up to about 20 metres across, and the one normally rigged; The Asterisk / Khoshilat Beya al Hiyool, 140 m; and Cheryl's Drop / Khoshilat Minqod, 158 m, only about two metres wide at the surface. The commonly quoted "150-metre abseil" is a conflation: the three drops are different, and the floor's lowest point lies some 178 metres below the highest entrance. This is single-rope technique with around 200 metres of rope, and the descent is the easy half — the prusik back out is a long, committing climb in free air. Getting to the rim. A rough single-lane track now climbs from near Tiwi, on the coast road between Muscat and Sur, up onto the plateau, and a competent 4×4 will reach the vicinity of the entrances. Before that road existed, the approach was a six-hour hike or hired donkeys from a village an hour and a half away — which, as showcaves.com dryly notes, did an effective job of filtering out the unprepared. Dale and Hadwin's Adventure Trekking in Oman describes a walking route from 'Umq to Ta'ab that passes the cave. The realistic visit, and the real danger. For all but a handful of trained cavers, the experience on offer is standing near the rim of a hole in open desert pavement. Take that seriously. The openings are unfenced, unmarked and overhung: Davison described the second pit he found as "ready to swallow the unsuspecting or clumsy", and the animal bones on the floor 120 metres below are what that phrase means in practice. Do not walk to the lip, and do not go near it in poor light. Practicalities. Permission is required and the situation has changed more than once; check current status with Oman's Ministry of Heritage and Tourism before travelling, and go with a licensed local operator if access is granted. Runoff pours into the shafts during storms — avoid the plateau in unsettled weather. If what you want is simply to see an Omani cave, Al Hoota Cave, near Al Hamra, is the country's developed show cave and needs no ropes.