Humans can breathe only a few things safely. One of those things is clean atmospheric air between sea level and ~4000 metres. Another one is oxygen, at a partial pressure between ~0.16 and 2.0 atmospheres of pressure (or 1.6 underwater, to be safer). Water is not one of them, nor any other pure gas.
It would be impossible to discuss all aspects of diving safety in one blog post. But here are a few of the biggest hazards that come to mind:
- You breathe something deadly (water, hypoxic gas, hyperoxic gas)–or can’t breathe at all.
- You ascend with closed airways, resulting in unrecoverable overexpansion injuries to the lungs, heart, organs and circulatory system.
- You ascend with gas bubbles trapped in your body, causing decompression injuries.
- You suffer a medical condition underwater, which might be unrecoverable in that environment (heart attacks, asthma…)
- You are carried away by currents, leading to disappearance, exposure, or injury.
- You become entrapped or entangled.
- You cannot return to the surface, due to overweighting, loss of buoyancy, or downcurrents.
- You become lost in a confined underwater environment, due to confusion, loss of light, and/or visibility.
- Contact with a moving boat or propeller while on the surface.
- Bodily injury upon entry or exit.
This actually breaks down the risks quite well into the straightforward hazards that should be at the front our minds when planning or executing any dive.
In some ways, it doesn’t seem so bad: rocks will not fall out of nowhere, you generally cannot slip and fall to your death (though there may be exceptions), you are not traveling fast enough for a collision to seriously injure or kill you (except in high surf), and sharks almost never attack divers. (Unless they are holding a speared fish.) You (hopefully) have a dive computer to monitor your depth and time, and a pressure gauge that easily confirms what you should already know about your supply of breathable gas.
But it is a heavy list. Now that diving looks like a terrible idea from a risk standpoint, what the heck are we thinking?
I am going to argue that the clear elements to safe diving are: awareness, risk assessment, decision making, proper training, equipment, and skills. In that order.
The above hazards have something in common: nearly all of them can be prevented by awareness, assessment, and decision making. With the except of a surprise heart attack in an otherwise healthy, asymptomatic diver, the life-threatening risks of diving are about what is happening in the space between our ears, before and during the dive.
The best instructor that I have had gave us a very important lesson: nearly all diving accidents begin on the surface, before entering the water. “Human Factors” is another way to put it.
This is a quite similar way of thinking to how avalanche safety is now taught, among many similar examples in different fields. Once you drop in, you have already made some of the most critical and consequential decisions about your safety. What happens next may now be unavoidable–as so many have learned.
Awareness
We can only mitigate the risks that we are aware of. Is the site safe to dive at this moment? What is down there? Do we know what the currents are doing? Are the waves too big, or will they be later on? Did you test whether your air supplies are fully open? Do you know how much pressure is in your tank right now? Am I familiar with my equipment? What depth are we going to? For how long? Are you certain that you know how to manage your buoyancy? Am I overweighted? Is there a leader on this dive? Is there a team? Do we have plans or resources for how to respond to an accident or separation?
Any “don’t know” could be a no-go. If you don’t know, don’t dive.
Assessment
So you are aware of the heavy list of hazards, and also aware of at least a dozen things that need to be assessed before you can dive safely. Did you actually assess them? Whose assessment are you following?
Decision Making
Everything about your dive is going to be your decision. How you set up, whom you dive with, whether to dive, what plan you follow, when to end the dive, what gear you use, what protocols to follow, how you respond to problems. Don’t give up this agency!
Does your dive buddy make your dive safer?
This is huge. Does your buddy make your dive safer? It is definitely not the case for everyone. You will undoubtedly encounter divers whose presence is reducing your safety. Whether it is from distraction, silting, poor communication, bad decision making, insistence on risky behavior, lack of awareness, loss of breathing gas, panic, or self-caused emergencies, the net affect on you will not be beneficial. This is not a safe dive buddy. They might be a student, a responsibility, or a liability.
What about a highly trained and skilled diver? Does that make them a safe diver and a good buddy? Not necessarily. In fact, a large number of accidents have occurred when experienced divers lack the awareness, assessment, or decision making skills to prevent accidents, particularly in ‘advanced’ or challenging conditions. It is common for a ‘skilled’ diver to lead other divers into challenging situations, and then leave them behind or fail to rescue their victim.
An excellent dive buddy is better than nobody at all. What is an excellent dive buddy? First and foremost, it is someone with high levels of awareness, the ability to assess risks–for all divers present–and the willingness to engage in honest decision making with everyone’s safety in mind. It helps if they are highly trained, skilled, and equipped.
Buddies need not match in every single way in order to dive safely together. What they do need is to honestly assess how to dive safely together, given what is at hand.
What is safety?
Some agencies promote that training, uniformity, repetition, and predictability is one of the surest paths to safety. This is of course recommended, useful, and necessary up to a point. Experience is also valuable, particularly experience with proper practices, but also with challenging situations.
However, you can also drive a car perfectly off of a cliff, especially when following other ‘perfect’ (or highly skilled) drivers. And the more certain they are of their skills, the nearer this situation might become.
I think that above all we first need to keep our minds trained on basic awareness and assessment of the hazards most likely to kill us (or our dive buddies) at any given moment. Go back to the list at the top. This is what actually matters. Tunneling in on the technical details of skill, objectives or performance can be a fatal distraction from simpler matters of higher consequence.
That may sound a bit dark for recreational diving, but it is a reality of the sport.
(The same is true about driving, if you think about it.)