This episode explores why experienced divers still die in situations that seem predictable, using the tragic 2026 Maldives cave accident as a starting point. It looks at how outcome bias, the normalisation of deviance, nitrogen narcosis, group dynamics, and silent drift can gradually erode safety margins without divers realising it. Rather than focusing on individual mistakes, the discussion explains how everyday decisions, accepted norms, and human psychology combine to create risk over time. It also examines what divers, teams, and the wider diving community can do to recognise these patterns, challenge unsafe habits, encourage open communication, and build a culture that learns from accidents instead of simply accepting them as bad luck.

Original blog: https://www.thehumandiver.com/post/we-know-and-we-say-nothing

Notes

  1. Concept formalised by Baron, J. & Hershey, J. C., "Outcome bias in decision evaluation," Journal of Personality and Social Psychology 54 (1988), p. 569-579. PDF available:https://www.sas.upenn.edu/~baron/papers/outcomebias.pdf
  2. Vaughan, D., The Challenger Launch Decision: Risky Technology, Culture, and Deviance at NASA, University of Chicago Press, 1996. Publisher page:https://press.uchicago.edu/ucp/books/book/chicago/C/bo22781921.html
  3. Lock, G., Under Pressure: Diving Deeper with Human Factors (2019); see also The Human Diver (https://www.thehumandiver.com) and the documentary If Only… (https://www.thehumandiver.com/ifonly).
  4. First systematic experimental demonstration: Behnke, A. R., Thomson, R. M. & Motley, E. P., "The psychologic effects from breathing air at 4 atmospheres pressure," American Journal of Physiology 112(3), 1935, p. 554-558. DOI:https://doi.org/10.1152/ajplegacy.1935.112.3.554
  5. For an overview, see Nitrogen Narcosis In Diving on StatPearls (NCBI/NIH):https://www.ncbi.nlm.nih.gov/books/NBK470304/; and Clark, J. E., Moving in extreme environments: inert gas narcosis and underwater activities, Extreme Physiology & Medicine 3 (2014), which establishes that narcosis directly contributes to up to 6% of diving deaths — free full text:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4337274/
  6. Hamilton, K., Laliberté, M. F. & Fowler, B., "Dissociation of the behavioral and subjective components of nitrogen narcosis and diver adaptation," Undersea & Hyperbaric Medicine 22(1), March 1995, p. 41-49 (PMID 7742709):https://pubmed.ncbi.nlm.nih.gov/7742709/


Bibliography

Decision biases, normalisation of deviance, human factors


Physiology of narcosis

  • Behnke, A. R., Thomson, R. M. & Motley, E. P., "The psychologic effects from breathing air at 4 atmospheres pressure," American Journal of Physiology 112(3), 1935, p. 554-558. First systematic experimental demonstration of the narcotic effects of compressed air at depth. DOI:https://doi.org/10.1152/ajplegacy.1935.112.3.554
  • Kirkland, P. J., Mathew, D., Modi, P. & Cooper, J. S., Nitrogen Narcosis In Diving, StatPearls (NCBI/NIH), last updated 2023:https://www.ncbi.nlm.nih.gov/books/NBK470304/
  • Clark, J. E., "Moving in extreme environments: inert gas narcosis and underwater activities," Extreme Physiology & Medicine 3 (2014). Free full text via PMC:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4337274/
  • Hamilton, K., Laliberté, M. F. & Fowler, B., "Dissociation of the behavioral and subjective components of nitrogen narcosis and diver adaptation," Undersea & Hyperbaric Medicine 22(1), March 1995, p. 41-49. PMID 7742709:https://pubmed.ncbi.nlm.nih.gov/7742709/


Diving accident research


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