Some sources attribute up to 200 divers having passed away at the Blue Hole. The vast majority are divers who attempt the dive in recreational gear and a single AL80 of gas. They secumb to recreational gear failure, out of gas, nitrogen narcosis, and oxygen toxicity. The bottom is very steep. The deceased often roll down the tube like area to the bottom at 300 feet to outside of the hole which is 600 feet. In the old days around 2010, according to author John Kean, two sometimes three divers a day would die in the Blue Hole. The authorities then started cracking down on unqualified divers diving the Arch. A Belgian diver was setting a depth record there and observed bodies and parts and coined the name of the divers graveyard.
There is a memorial wall dedicated to the fallen divers near the Blue Hole. Sometime around 2011, the authorities banned families and friends from putting up additional plaques. But apparently that is being ignored to some extent as some more recent plaques have been emplaced.
With the proper technical training, equipment, and technique, the dive is actually no more hazardous than any other dive to that depth. It used to be that the most dangerous part of that dive was falling down due to the flip flops on the 30 foot path down to the water. Since 2019, on our first trip there, they have now added sets of steps to both entrances, so it is that much safer.
We were there last week and I posted a video on our group diving the blue hole arch in the tec trips section. Here is the link.