Thanks Wantonmien.
Mean Guy, the blue hole is a very challenging dive on a single tank.
The arch leading to the open sea starts at 56 metres and stretches for 25 metres long although it feels and looks like only five meters.
Coming up the the other side of the arch there is almost always a down current. So you've got an overhead environment, depth, down current and to cap it all if you get bent the trip over the mountains to get to the chamber would kill you. Lots of people have died trying to find the arch, get narked and then run out of air.
A guy died a few years ago there and his father sent an ROV to look for the body. There was enough kit down there from divers who had perished to fill out 2 dive centres.
Like I said lots of graves in the desert cliffs.
It should not be attempted with going tech or the right guide.
I have a video of us doing it a few years ago but Ive promised not to post it on the internet as it clearly identifies people who live there and could get in big trouble.