When I lived in St Croix, our crew became good friends with the guy that owned VI Divers. When he would get large parties of divers to take out, if it was on the weekends, several of us would go along to keep an eye on the tourists. The worst were the certified instructors from Florida. They are use to shallow water divers in comparison to the islands which are nothing more than the peak of an undersea mountain. They would go down three times the depth they are use to and then forget to decompress.
The easiest tourists to manage seemed to be the newcomers. They were always double checking their gear, dive tables, etc. The more experienced they were the more comfort they had and would take more changes.
Deepest dive I have made was to 205 feet. Went through a 80cuft tank in less than 10 minutes trying to watch my breathing (2500psi to 250psi). As I said before I got my certification on the island. My instructor had worked one season with Cousteau and could stretch her tank out by controlling her breathing. We use to see who could make a tank last longer. We had placed tanks at 30 & 15 feet for decompression. I accessed both. We had a certified dive doctor on board and everything was planned as a recovery for lost equipment. Not a dive you do on a whim.
They use to have drops that you could put in your ears to help clear them and make it easier to neutralize the pressure. A buddy of mine also had trouble and use to use hot water in a cup, he would lay on his side and place his ear in the cup, not in the water, and let the steam help clear his ears before we dove. Just be careful not to tip the cup over.