I am one dive away from completing my Stress & Rescue specialty. The other day, as my instructor and “victim” threw scenarios at me, something interesting happened: my dive buddy became positively buoyant during our 5-meter safety stop and almost surfaced.
I saw him ascending, raced over to him, grabbed his Buoyancy Compensator Device (BCD), and then dumped air from my BCD while fully exhaling. This created enough negative buoyancy, along with my dive buddy dumping air from his BCD, for both of us to become negatively buoyant enough to descend back down to 5 meters.
I immediately began thinking that this was the second dive day in a row that I had to do this. I also thought about how I used to struggle at my safety stops before I was properly weighted and understood how to control my buoyancy using my lungs.
So, even though the digital textbooks say that decompression sickness is the most common issue to worry about, I disagree. In my admittedly-limited experience, I would say that buoyancy issues are the biggest concern.
Yes, the problem with positive buoyancy is the risk of decompression illness. However, I have observed issues with negative buoyancy, as well. Negatively-buoyant divers who drift along a coral-covered wall do not necessarily notice that they are at 20 meters… then 25… then 30… then, in one case, 45 meters. This happened to a young, inexperienced diver who had not trained for diving to that depth. He also did not have a dive computer.
Plus, let’s not gloss over the damage divers can do to corals when they lack the skill to maintain neutral buoyancy.
Therefore, I rank buoyancy issues — positive, negative, and neutral (or lack thereof) — as the most common issues to be concerned about.