Human Factors in Diving
What Human Factors Actually Means
Human factors is the combination of psychological, cognitive, and social elements that shape diver behavior. It is not about blaming individuals. It is about understanding why a decision made sense at the moment it was made. When divers understand those influences, they catch more problems early and avoid the errors that escalate into incidents.
How Decisions Unravel Underwater
Divers make decisions under time pressure, limited visibility, physical workload, and stress. These conditions push the brain toward fast, intuitive thinking. This is efficient but error-prone. When overloaded, divers focus on the nearest task and lose the bigger picture. Small issues stack together, and by the time a diver realizes something is wrong, the real problem started much earlier.
- Assumptions: Believing conditions are stable or thinking the buddy is behind you when you have not checked.
- Biases: Continuing the dive because you want the outcome you planned for. Overconfidence after several uneventful dives.
- Stress: Cold, current, or equipment issues shrink attention and make people miss simple cues.
- Social pressure: Following an experienced diver or staying silent because you do not want to delay the group.
- Mismatched mental models: Using past experiences in a new situation where they no longer apply.
These are not failings. They are predictable human patterns. Recognizing them is the first step toward managing them.
Situational Awareness and Capacity
Situation awareness has three parts: noticing what is happening, understanding what it means, and anticipating what will happen next. Beginners often lose awareness because all their capacity is consumed by buoyancy, trim, equalization, and breathing. When your bandwidth is full, your awareness contracts. You cannot respond to what you do not notice. See Situation Awareness for Divers for more detail.
Team Dynamics and Social Intelligence
Strong teams outperform strong individuals. Team performance depends on trust, communication, and the ability to read subtle cues. Social intelligence allows divers to notice hesitation, anxiety, or confusion before it becomes a problem. Good teams adjust early, ask questions, and keep each other informed. Poor teams hide uncertainty, fall silent, and drift into trouble.
Psychological Safety and Just Culture
Divers speak up only when they believe it is safe to do so. Psychological safety means anyone can ask questions, raise concerns, or call a dive without ridicule or social penalty. Just Culture means mistakes are discussed openly to understand the conditions that created them, while still holding people accountable for reckless choices. Together they create teams that learn instead of teams that hide problems. See Calling a Dive for how this applies in practice.
Normalization of Deviance
When divers repeatedly bend a rule without negative outcomes, the deviation becomes normal. This drift is subtle. A diver surfaces several times with 500 psi and nothing goes wrong. They start surfacing with 400 psi, then 300. Others see it and follow. The absence of failure masks the increase in risk. Drift is prevented by clear procedures, agreed-upon plans, and regular debriefs that reset the baseline of what “normal” should be.
Reflection: How Divers Actually Improve
Most learning happens after the dive. A structured debrief compares the plan with the reality, examines what went well and why, identifies what needs improvement, and updates mental models for next time. Without reflection, divers repeat the same assumptions and normalize the same shortcuts.
Why This Matters
Human factors are not academic theory. They are the practical limits of human attention, memory, perception, and behavior under pressure. When divers understand how those factors shape their decisions, they stop relying on luck and start relying on awareness, communication, and disciplined habits.
The goal is simple: fewer surprises, earlier corrections, and better decisions underwater.
Learn More
The leading source for human factors in diving is Gareth Lock and The Human Diver. His book, Under Pressure, and the online course, Human Factors in Diving: Essentials, give divers usable tools for improving decision-making, awareness, and team performance.
I completed the Essentials course myself. It remains the single most valuable non-skill training I have taken as a diver. It changed how I think about preparation, how I evaluate my own decisions, and how I dive with others.