Human factors examines how attention, memory, stress, assumptions, and social pressure influence divers and their teams. Decisions that look obviously wrong afterward often seemed reasonable to the people making them. Understanding the conditions behind an error, including the environment, equipment, and team, is more useful than merely telling divers to be careful.
Why Reasonable Decisions Go Wrong
Imagine a group preparing to enter the water. Conditions have deteriorated, the boat is behind schedule, and nobody wants to cause a delay. Each diver notices something different, but assumes somebody else would speak up if there were a real problem. The team enters with less margin than planned, even though no one set out to take an unreasonable risk.
Cold, current, low visibility, and unfamiliar equipment compete for attention. Previous successful dives can make questionable practices feel acceptable, while social pressure discourages questions. We also interpret new situations through past experience, even when circumstances have changed. Experience alone doesn't make those tendencies disappear.
Attention Is a Limited Resource
Situation awareness involves noticing what's happening, understanding what it means, and anticipating what may happen next. When a diver is occupied with buoyancy, equipment, or an unexpected problem, less attention remains for gas, depth, the environment, and the buddy. You cannot respond to a warning you never noticed.
Regular instrument checks, agreed procedures, and a clear briefing reduce the demands on attention and memory. They don't guarantee awareness, but they make important information harder to overlook. I've explored the subject separately in Situation Awareness.
A Team Must Be Able to Speak Up
A buddy may recognize trouble long before an alarm sounds, but that observation is useless if they don't feel able to mention it. Good teams ask questions, acknowledge uncertainty, and allow any diver to question the plan or end the dive without argument.
Psychological safety makes those conversations possible. Alongside it, Just Culture examines mistakes and their contributing conditions without excusing reckless behavior. Both help people speak while there is still time to call the dive or change the plan.
When Shortcuts Become Normal
A diver surfaces below the planned gas reserve and nothing goes wrong. It happens again, and the lower reserve gradually begins to feel acceptable. This is normalization of deviance: repeated success disguises a practice that has drifted away from the agreed limits.
Checklists, clear procedures, and honest briefings help reveal that drift. When the plan changes, the team should discuss the change rather than quietly redefining what is normal. A good outcome doesn't necessarily mean the decision was sound.
Learn From the Dive You Actually Had
A debrief compares the plan with what happened. Were gas checks timely? Did someone hesitate to raise a concern? Did the team adapt deliberately, or simply get away with a shortcut? Those questions matter even after an uneventful dive.
A structured debrief looks for contributing conditions and identifies what should change next time. Its purpose is neither assigning blame nor praising a lucky outcome. It is improving the decisions the team will make on its next dive.
The Training That Changed My Approach
Gareth Lock's The Human Diver applies human factors to scuba diving through his book Under Pressure and the Human Factors in Diving: Essentials course. These resources provide practical ways to examine awareness, decisions, communication, and team performance.
I completed Essentials myself, and it remains the most valuable non-skill training I've taken as a diver. It changed how I prepare, evaluate decisions, and dive with others. As a Human Diver Ambassador, Dive Otter sponsors members of the Mid-West Underwater Explorers community who want to take the course.
Human factors won't prevent every mistake. Understanding them gives divers a better chance to notice when a routine dive is becoming a difficult one, speak up, and correct course before the options narrow.