Not long ago, I overheard a heated discussion between dive buddies about whether most accidents are due to plain 'human error' or just bad luck. It instantly reminded me of my own rookie panic on a murky lake dive, where, despite every checklist and gear check, I realized my head was my biggest risk factor. Gareth Lock's "Under Pressure" takes this idea further—ripping apart the myth that mistakes are black-and-white or purely technical failures. Lock invites readers into a world where what really happens under the surface hinges not only on skill, but on mindset, communication, and culture. Pull up a chair (or a tank)—let’s get beneath the headlines.
1. Why Most Diving Accidents Aren’t What You Think (And Why That Matters)
For decades, the diving community—like many high-risk industries—has leaned on a simple explanation for accidents: “human error.” In the 1970s and 1980s, both aviation and diving safety experts cited the same statistic: 80% of incidents were blamed on human error. But as Gareth Lock reveals in Under Pressure: Diving Deeper with Human Factors, this old way of thinking is not only outdated, it’s dangerously incomplete.
Lock draws on his background as a military aviator to show that diving safety performance is about much more than following checklists or having the right gear. In aviation, blaming the pilot was once common. But since the 1990s, safety leaders have recognized that accidents are rarely the result of a single mistake. Instead, they’re the end result of a chain of decisions, miscommunications, and system-level factors. This systems-thinking approach—now standard in aviation and healthcare—has only recently begun to reshape how we understand diving incidents.
Lock’s book is packed with over 30 real-world case studies, each showing how even small, seemingly harmless choices can add up. Take, for example, the story of a diver who nearly skipped a safety stop after a minor equipment issue. On the surface, it looks like a simple lapse in judgment. But Lock digs deeper: Was the diver rushed by the group? Was there pressure to “not be the slow one”? Did unclear communication or a lack of psychological safety make it hard to speak up? These are the human factors in diving that often go unnoticed until something goes wrong.
“Mistakes aren’t just bad luck—they’re signposts for where procedures and thinking need an upgrade.” – Gareth Lock
Lock’s approach moves beyond the blame game. Instead of asking, “Who messed up?” he asks, “What set the stage for this decision?” This mindset shift is crucial. When we focus only on individual errors, we miss the bigger picture: Decision-making under pressure is shaped by stress, fatigue, team dynamics, and even the culture of the dive shop or training agency.
By highlighting these high-risk industries safety lessons, Lock challenges divers to look at the whole system. He encourages open discussion of near-misses and honest debriefs, not to assign blame, but to learn and improve. The book’s 13 chapters are structured to help divers, instructors, and teams recognize and manage these hidden risks—turning every mistake into a chance for growth.
Ultimately, Lock’s message is clear: If we want to prevent accidents, we need to stop blaming individuals and start understanding the complex web of factors that drive our choices underwater. That’s what makes Under Pressure a game-changer for anyone serious about diving safety performance—and for anyone who wants to make better decisions under pressure, both in and out of the water.
2. "Just Culture" and the Myth of Blame-Free Diving
One of the most powerful lessons in Gareth Lock’s Under Pressure is the idea that talking openly about mistakes is nothing short of revolutionary for diving culture. For decades, the diving community—like aviation before it—has clung to the myth that only “bad” or “inexperienced” divers make errors. Lock’s deep dive into Just culture diving shatters this illusion, showing that even the world’s best, like Jill Heinerth and Steve Bogaerts, have faced moments where things didn’t go as planned.
Through more than 30 case studies diving incidents, Lock demonstrates that mistakes are not a sign of incompetence, but a natural part of complex, high-risk environments. These real-world stories make errors relatable and instructive, breaking down the myth of infallible divers. As Michael Menduno (M2) puts it:
"Safe teams aren’t perfect—they’re honest about their imperfections."
This honesty is the heart of Diving culture improvement. Lock’s vision of a Just Culture is not about being “blame-free” or ignoring responsibility. Instead, it’s about creating an environment where divers—whether they’re new to the sport or seasoned pros—can discuss near-misses and accidents without fear of backlash. This openness is essential for psychological safety diving; after all, no one wants to admit mistakes if they expect to be shamed or punished.
Lock draws a creative analogy: diving teams are like jazz bands. Each diver brings their own skills and style, but when the unexpected happens, it’s the group’s ability to improvise, communicate, and adapt that determines the outcome. In a jazz band, mistakes are not hidden—they’re woven into the music, creating new possibilities. Similarly, in diving, sharing and analyzing errors openly leads to improved safety practices and diving community learning.
The book’s case studies are especially powerful because they feature legends like Jill Heinerth and Steve Bogaerts admitting to “messing up.” These stories strip away the pressure to be perfect and encourage all divers to dig into what really happened, why, and how to prevent it next time. This approach moves the community beyond a culture of blame to one of curiosity and learning.
Lock’s advocacy for Just culture diving is echoed by industry leaders—Mark Powell, Phil Short, Richie Kohler, Doug Ebersole, Lanny Vogel, Steve Millard, and Chantelle Taylor-Newman all endorse the book’s message. They recognize that when divers feel safe to speak up, everyone benefits. The Under Pressure digital community extends this vision globally, giving divers a space to share stories, reflect, and build collective wisdom.
Ultimately, Under Pressure shows that embracing mistakes—rather than hiding them—is the key to safer, more resilient diving teams. By fostering psychological safety and open dialogue, the diving community can improvise, adapt, and thrive, just like the best jazz ensembles.
3. The Human Toolbox: Beyond Dive Computers and Checklists
In Under Pressure: Diving Deeper with Human Factors, Gareth Lock makes a bold claim: “Non-technical skills are the true redundant system—when your gear can’t save you, your thinking might.” This insight reframes how divers should approach safety. While dive computers and checklists are essential, Lock argues that the real backbone of safe diving lies in the human toolbox—skills like communication, teamwork, self-awareness, and decision-making under stress.
Non-Technical Skills: The Hidden Lifeline
Lock’s research shows that non-technical skills divers develop—such as clear communication and effective teamwork—are often the difference between a close call and a catastrophe. Drawing from high-reliability industries like aviation and healthcare, he demonstrates that technical expertise alone isn’t enough. Instead, it’s the ability to work together, stay aware, and adapt that keeps teams safe underwater.
Communication diving teams: Structured communication, including pre-dive briefs and post-dive debriefs, helps ensure everyone is on the same page. Lock likens a good dive brief to prepping for surgery—no detail is too small to discuss.
Teamwork and Leadership Followership Diving: Leadership isn’t just about giving orders. Effective leaders and followers both contribute to a culture where questions and concerns are welcomed, not silenced.
Self-awareness and Performance Shaping Factors: Recognizing how stress, fatigue, and even overconfidence can shape decisions is critical. Lock provides practical tools for managing these factors before they become risks.
Decision-Making Frameworks: More Vital Than Equipment
One of the book’s standout frameworks is “What? So What? Now What?” This simple, three-step process helps divers pause, assess, and act—especially when stress levels spike. In emergencies, the ability to slow down and make sense of what’s happening can be more vital than any piece of equipment.
Non-technical skills are the true redundant system—when your gear can’t save you, your thinking might.
– Gareth Lock
Building a Just Culture: Safety Through Honesty
Lock advocates for a “Just Culture” where divers feel safe to share mistakes and near-misses without fear of blame. This openness allows teams to learn and improve together. Leaders and followers alike can nudge the culture toward honesty and safety by encouraging open dialogue and reflective debriefs.
Actionable Guidance, Not Just Theory
Each chapter in Under Pressure ends with practical summaries, making it easy for readers to apply what they’ve learned. The book covers real-world topics like stress management diving, performance-shaping factors, and step-by-step communication tools. Digital resources and an active online community further support divers in mastering these essential skills.
Lock’s message is clear: mastering the human toolbox is not just for emergencies—it’s the foundation of safer, more effective diving and leadership, both underwater and in life.
4. Learning from Failure: Does Your Dive Log Tell the Whole Story?
In Under Pressure: Diving Deeper with Human Factors, Gareth Lock flips the script on how divers—and anyone in high-risk environments—think about mistakes. Instead of treating failures as shameful secrets, Lock’s approach is clear: owning mistakes beats hiding them. The book’s real-world stories, shared by elite divers like Jill Heinerth and Steve Bogaerts, show that even the best make errors. What sets them apart isn’t perfection, but their willingness to reflect, share, and learn. As Chantelle Taylor-Newman puts it:
"What makes a great diver? The willingness to put ego aside and turn failure into knowledge."
Lock’s message is simple but powerful: Living with failure is not about accepting defeat, but about embracing the error learning process. Every close call, every minor mishap, is fuel for growth—if we’re honest about what happened. This mindset shift is at the heart of diving culture improvement and diving incident prevention.
What If Your Dive Log Tracked More Than Depth?
Imagine if every diver’s logbook included not just the usual stats—max depth, bottom time—but also a frank account of what went sideways. What if “near-miss” and “lesson learned” became as routine as “air used”? Lock argues that this kind of transparency would transform the sport. Instead of a culture where mistakes are whispered about (or ignored), we’d have a community where open discussion of errors is normal—and safety innovation accelerates.
Failures become learning fuel, not destiny.
Reflecting on close calls (not just heroics) is how culture improves.
Normalizing open discussion of mistakes accelerates safety innovation.
This isn’t just theory. Lock’s advocacy for a “Just Culture” has already inspired safer practices in fields like emergency medicine and healthcare, where professionals now debrief not just on what went right, but what nearly went wrong. Endorsements from emergency medicine experts highlight how these lessons ripple far beyond diving.
From Shame to Shared Wisdom
Lock’s case studies reveal that most diving incidents are not the result of a single “bad apple” or reckless act. Instead, they’re the outcome of small, often well-intentioned decisions that stack up over time. By documenting and discussing these moments—without blame—divers can spot patterns and prevent future incidents. It’s a process that demands humility, but the rewards are huge: safer dives, stronger teams, and a more resilient community.
For instructors and agencies, the book’s lessons are easy to share. Bulk and custom orders (from £30.00 UK, £45.00 overseas) make it simple to integrate this mindset into training at every level. After all, as Lock and his supporters remind us, the real story of a dive isn’t just in the numbers—it’s in the lessons learned when things don’t go as planned.
5. Closing the Loop: Building a Lifelong Community of Safer (and Happier) Divers
Gareth Lock, author of Under Pressure: Diving Deeper with Human Factors, has done more than write a book—he’s sparked a movement. By blending his military aviation background with deep experience in technical diving training and trimix diving certification, Lock brings a unique, humble mentorship to the diving world. He’s not a know-it-all; instead, he’s a relentless advocate for learning, echoing Mark Powell’s insight:
“The world’s best divers aren’t fearless—they’re relentless learners.”
What truly sets Under Pressure apart is its commitment to community-building. Lock’s vision extends far beyond the pages. Through an active digital platform, readers and divers worldwide can connect, share stories, and reflect on real-life incidents. This online community is where the book’s philosophy comes alive—transforming theory into everyday practice. Here, divers of all backgrounds, from those just starting technical diving training to seasoned instructors with trimix diving certification, can learn from each other’s experiences, ask questions, and grow together.
This approach is central to sustained safety improvement. By fostering open dialogue and a “Just Culture,” Lock encourages the diving community to move past blame and instead focus on learning. Mistakes and near-misses become valuable teaching moments, not sources of shame. This culture of psychological safety is what allows best practices to evolve and spread, making every dive—and every diver—safer.
The reach of Under Pressure is truly global. Whether you’re in the UK, the US, or anywhere else, the book is accessible in print (including signed copies from Gareth Lock himself), Audible, Kindle, iBooks, and through major retailers like Amazon, Target, and Barnes & Noble. With prices set at £30 for UK and pick-up, £30 including postage and packing, and £45 for overseas orders, it’s never been easier for individuals, teams, and instructors to integrate these lessons into their training. Bulk and custom orders are encouraged, making it a practical resource for diving schools and agencies worldwide.
Ultimately, Under Pressure is more than a manual for safer diving—it’s a catalyst for cultural change. By closing the loop between learning, sharing, and applying lessons, Lock’s work empowers divers to become not just safer, but more confident and happier, both underwater and in life. The diving community learning fostered here is ongoing and inclusive, ensuring that the pursuit of safety and excellence never stops. With Gareth Lock as a mentor and a global network at your fingertips, the journey toward high-performance, resilient diving is open to all—today and for a lifetime.
