Fear shuts down thought. Under conditions of intense fear, the amygdala activates the locus ceruleus, which releases high levels of noradrenaline in the prefrontal cortex. This works to deactivate the whole of the lateral prefrontal cortex. In essence, the fear system pulls the plug on all our higher-level cognitive processes. The time to make a plan is not when you wake up inside a burning building.
Unfortunately, most of us have a hard time appreciating before the fact how non-negotiable this effect will be. That failure can result in tragic consequences – especially when it comes to one particular recreational activity that demands self-reliance in a potentially fatal environment. What is it?
Cave diving. The underwater environment is inherently stressful; add in the strange sensation of weightlessness, the cold of the water, the constriction of the wetsuit and other gear, and the restricted vision, and the psychological load is even heavier. One of the major side-effects of stress is rapid breathing. In the grip of panic, a person fighting fighting for air will instinctively rip away anything that’s blocking his mouth. Unfortunately for scuba divers, that thing is the regulator that supplies their air. Thus a situation that in itself might only be mildly stressful or scary can quickly spiral into a fatal spasm of panic. Sports psychologist William Morgan, who spent 10 years studying scuba panic at the University of Wisconsin, suggested that panic may play a part in as much as 60 percent of all underwater fatalities.
A particular dangerous variant is cave diving. The sensation that one is trapped inside one’s environment can be intensely stressful. This is bad enough when you’re under 100 feet of water, but all the more so when you find yourself in a long, dark cave, separated from the safety of the surface by solid rock. Worse, underwater cave bottoms are often covered in fine silt, which is easily stirred up to produce a disorienting blackout effect, very much like the spatial disorientation effect that can be so deadly for pilots. When you’re scuba diving deep in a cave, the slightest twinge of anxiety can quickly spin into a catastrophe from which there is no escape.
On Easter Sunday, 1992, a 26-year-old Australian spelunker named Rolf Adams prepared to enter the water of Jackson Blue Spring, a long, deep lake in the Florida panhandle whose crystalline waters concealed an intricate network of caves. An expert in exploring dry caves, Adams had signed up with cave explorer Bill Stone for expedition to the bottom of Sistema Huatla, a labyrinth of flooded caverns that lies beneath the Sierra Mazateca mountains near Oaxaca, Mexico. It was the last day of a five-week training camp. The next day, they were scheduled to leave for Mexico. Adams was eager to get as much practice in as possible.
Accompanied by Jim Smith, an experienced cave diver, Adams entered the water and finned to the entrance of Hole in the Wall, a cave outfitted with a fixed line that ran to its bottom. Adams and Smith followed the line about 2000 feet in, then turned around to come back out. When they were still 1000 feet from the cave mouth, Smith turned to check on his buddy and found that he had floated to the roof of the cave, where he was exchanging his primary regulator for his backup one. Having accomplished that, he signaled to Smith that he was okay. Smith turned and continued to swim for the entrance. Moments later Adams caught up with him, gesturing frantically: he was out of air. Calmly, the experienced Smith handed Adams his regulator to breathe from, and began breathing from his own backup regulator. As the switch was underway the two men, distracted, were unable to maintain their buoyancy, and slowly sank to the cave floor. Stirred by their motion, the fine silt that had gathered there over the years billowed up and surrounded them. Now the men overcompensated for their buoyancy, and floated to the cave ceiling. The regulator fell out of Adams’ mouth, he pulled away from Smith, and disappeared into the murk.
Managing to reorient himself toward the entrance, Smith swam for safety and barely managed to make it clear of the cave mouth. Virtually no air remained in his tank. When Adams’ body was recovered, his equipment turned out to be working just fine, and his tank had plenty of air. What had killed him wasn’t his lungs, but his brain – inexperience and stress compounded by disorientation, claustrophobia, and sensory deprivation.
Panic is far from rare among scuba divers. One survey conducted by Morgan found that more than half experience panic or near-panic at least once. A cave diver’s vulnerability to anxiety and panic is so amplified that even the most steely-nerved veteran is in danger of succumbing. Indeed, Morgan found that divers with extensive experience could find themselves panicking for no obvious reason. A notable case in point was the man who was sent in to recover Adams’s body, Sheck Exley. Tragically, Exley himself was found dead two years later at the bottom of another deep cave – despite having 29 years’ experience, and being regarded as one of the most skilled and knowledgeable cave divers in the world.