Dark water diving initially to me was night diving. I have done a few dives in semi clear water with the worst being a few feet of visibility. Recently we did a training dive at Bear Lake and I got to experience what dark water diving was like. It was a sunny day, as we descended with our lights. At about 20' it was almost pitch black and I needed a light to see anything. As we went further down on the anchor line visibility went to near 0. I could not see my hand or anything else for that matter. Even with my trusty dive light there
I recently had the opportunity to dive in one of our local rivers, the Tuckasegee. It was very close to dark by the time we arrived. There were three divers affording us a safety diver and several SRT (Swift-water Rescue Technicians) on the bank. Since at least two of us had never been diving in this kind of current much less in the dark it seemed we were well prepared.
It was a cold night in the 50's and the water temp according to my Suunoto gage was 43 degrees. I had all of my 7mm gear on but could certainly feel the cold water. One difficulty I hadn't thought about was getting myself in a 7mm suit with booties, no less, down to the dive site with my equipment. We had some dive handlers that helped but it was a careful stroll down the embankment thru heavy brush to get to the waters edge. Not something that was particularly fun in a wetsuit and booties.
After getting our gear on someone who knew how to do this gave us some quick advice and made it a point that it was just that, advice. He reiterated a few times that it was an acquired skill diving in current and navigating to the bottom. I of course had no real idea what he was talking about I just knew I was going to do my best to apply what he was saying once I got out there.
We had a target area about 25 feet out in the river we wanted to go over well. Initially I went up stream a bit then attempted to descend and begin the search. I quickly floated downstream past our target area and had to swim to the edge and walk back up. Not something with scuba gear on your back you would like to do many times in a row.
Second try, I went a bit further and tried to visualize my speed vs where I went at to determine if I was going to over shoot. First I dipped down into the water and completely emptied my BC, snagged an additional 8 lbs of weight as I walked by the bag, and found the secret. What is that you ask, well head down butt up is the best way I know to describe it. I forced my head down to the bottom. The current took care of getting the rest of me planted well enough with the pressure of the current pushing down on me to hold me in place. I could now crawl around and examine the bottom.
First small problem that arises. Am I even at the target site? I browsed around for a bit and realized if i didn't keep my body laid out the way it was I would be whisked off downstream. Struggling around I finally noticed some light from the bank and used the lines of wash to establish I was near slightly upstream from the target area. The important point here is use the lines of the wash underwater to use a parallels along with light source on bank to tell where you are. I searched much of the target area and was able to hand around for about 10 minutes before making a mistake move that whisked me away quickly downstream.
Walking back up, I shared what I had learnt and headed back upstream. This time I perfectly "landed" the target area and reproduced it several times until I ran out of air and we packed up for the night. With each dive I got better and better at managing the current, my position, and my dive light. The only scary part of the night came while I was at about 15 feet searching. I was windshield wiper searching the bottom and suddenly a bright rainbow flash was suddenly right next to my head. It was a 12-16 inch rainbow trout swimming happily right next to my head. I almost spit the reg from my mouth. He just hovered around me like I was supposed to be in the water.