Majlis al-Djinn cave closed
If you are able to track down a copy, the reference to this brochure is:
Davison Jr, W. Don 1985 Majlis Al Jinn Cave, Sultanate of Oman Public Authority for Water Resources, Report PAWR-20, October 1985
Adventure and ecotourism companies are irked, apparently, because they can no longer take paying visitors to go and see the site. I have some sympathy with the authorities over this. It's far more clear-cut to issue a total ban, rather than a permissive one when rangers might not be able to argue over permits and safety measures with persuasive guides. The location of the cave is relatively remote. Should a rescue operation be required, I suspect the public cost and logistics would be deemed untenable.
No such foibles seem to deter trekkers on the Snake Gorge challenge in Wadi bani Awf, which carves through the Al Hajar mountains south of Rustaq. You will note a warning on the page that the walk is dangerous. A friend of mine had to be airlifted out in 2001 after he misjudged a jump from a rock into a pool and hurt his back seriously.
I also remember the tragedy of June 1996 when eight hikers were swept down the gorge and drowned in a flash flood. I happen to remember returning from a walk on the beach in Muscat before 10 am that morning. Already, the clouds were tumbling over the top of the mountains, a sure sign of thunderstorms and rain later in the day.
Never be caught in a wadi if there is the slightest suspicion of rain.


http://uk.youtube.com/watch...
[ed. And if you want to know what the video is about, it's a Red Bull sponsored base jump into Majlis al-Djinn cave. The jumper said it's a very difficult jump - only 100m, dark and no clear idea of the landing ground.]