Reminds me of my first dive after certifying. I went to Belize with my lds - not knowing anyone except the owners - who were on the other boat. We went down and followed the DM. I was back a bit and didn't see him enter a looong swimthrough. Everyone went in one at a time. I was at the end of the line thinking oh great. They are disappearing into this cave and I have no idea where they will come out. Then I'll be alone on the bottom of the freaking ocean and I don't even know for certain where the boat is! There had been NO dive briefing. Fortunately I had a little light in my bc pocket so I just lit it up and followed the last pair of fins I could see. When we came out it was more blue and green. A quick look at my computer confirmed we were at 94 feet. I thought "great,first dive I do av overhead environment dive and go 94 feet, what do I do for an encore". I'm still not sure I wouldn't do it again given the situation I found myself in. Ah well, live and learn, assuming you live of course.