I am in no way trying to put down the divers that have passed there, my heart & prayers go out to the divers & their families, but at least 3 of the deaths look to be diver error. If I remember correctly the two that passed in April did not have cold water equipment & at the time (I haven't read or heard any more about it any time lately) that they may not have been trained in deep diving (if I'm wrong on this please feel free to correct me on it). I'll admit I really haven't kept up on that particular topic. In the last incident it says that the diver was found away from her group. It doesn't say how long she was away (it may never be known), but most agencies train that if you're separated from your buddy (or maybe in this case your group) to look for 1 min. then make a safe ascent & wait at the surface. The same goes for a group. There should be periodic head counts to verify everyone is there. A problem can occur in a very short period of time at depth & in the cold, which emphasizes the importance of sticking close to your buddy or group, especially at depth. I commonly dive in a deep quarry just a few hours away from Gilboa in KY & the conditions are very similar. When the people I dive with down there decide to go as a group, we do the group in buddy pairs or threesomes (as needed), as we had a rather bad separation problem of the group on one particular dive, & though we were lucky that no one go hurt or worse, we learned our lesson. In that event, everyone followed their training & looked for 1 min. then surfaced safely. Now by keeping the buddy pairs or threesomes in a group, even if we get separated as a group, we can safely continue the dive. What I'm trying to say in the end, is from what I've read at least the 3 deaths don't seem to have been caused by anything the operators could control. From their web site pages, they seem to have a comprehensive preparation list & submission of a deep dive plan to dive deep, but that's not really going to stop anyone who wants to do it form just going ahead & going deep. They can't police everyone all the time. As those who do it know, cold deep quarry diving can be done relatively safely when there is proper training, a thorough dive plan & everyone "plays by the plan & the rules of diving", not to say that there still can't be problems, injuries or even, God forbid, fatalities even with the best training, equipment, plan & divers, but when you have all these things in place, the deep & the cold can be a cool place to check out.