"Forgot that air supply runs out faster the deeper you are." I ran into this one on my certification dive; we were diving on the Madera in Lake Superior in Dec

"Forgot that air supply runs out faster the deeper you are." I ran into this one on my certification dive; we were diving on the Madera in Lake Superior in December, I was having trouble keeping my bouyancy which I chalked up to inexperience but later discovered was a leaky BCD. When we went to move to the stern which is in 60 feet of water we all checked our air and I had a quarter of a tank left! Everyone else had at least three quarters of a tank. None the less, the rest of the dive was called off and we had to swim back to shore. I asked why we didn't at least try the deeper dive and he reminded me that you consume much more air in deeper water, pretty much double every 30 feet, that we wouldn't have even made it to the stern before I ran out.