Divers Exploring Human Depth Limits

The group was divided. Many were apprehensive. “Each person must make their own choice,” Stone stated. “The Pearse Resurgence is not suitable for experimentations. Upon entering, you should utilize equipment and methods you are confident will function at such a depth. Conducting physiological tests at a 300 meters’ depth is unadvised. This has proven fatal for divers who ventured beyond 200 meters. Hence, my counsel to Harry or anyone else considering this endeavor is identical to my advice to Exley: Simulate this beforehand in a pressure chamber.” “There was a divergence of views within the group,” Menduno shared. “While everyone was backing Harry, some worried about his survival. Some were anxious and troubled over the possibility of their friend undertaking such a potentially deadly mission.”

As you approach the first bend of the Pearse Resurgence, the light fades as if absorbed by the dark, striated marble walls of black and gray quartz. The cave fluctuates in size, from narrow spaces where the rooftop is within reach to large chambers. At a certain location, sharp protrusions of rock extend from the walls. Deeper segments of the cave are smooth and nearly circular, disrupted only by dark crevices leading to uncharted passages. Each explored section of the cave is named accordingly. During their dive in February 2023, Harris and Challen navigated through the Nightmare Crescent, Needlebender, Gargleblaster, Weaver’s Ledge, the Big Room, and eventually, the Brooklyn Exit. The water measured 6 °C and was transparent. Apart from the subtle sounds of the rebreathers—an occasional crackle or quiet hissing noise—it was eerily silent.

At a depth of 120 meters, the cave expands onto a cliff edge which leads to a chasm. “It feels like the adventure is truly starting when you reach this point,” Harris revealed. The chasm becomes a vertical tunnel that drops down 50 meters. By 170 meters, Harris could orient himself by recognizing specific rock formations. To conserve energy and minimize carbon dioxide accumulation, their movement was restricted, as they made use of underwater scooters for traversing. They periodically secured their location during the descent, navigating around previous ropes, with some dating back 20 years from Doolette’s visits.

At 230 meters, Harris achieved a first—descending to exceptional depths while freely swimming and breathing in hydrogen. Despite being hyper-focused on their meticulous plan and any anomaly in his rebreather that could indicate a problem, he took a moment to envision the sight. He questioned: “What if I’m unable to witness this again?” He initiated hydrogen use at 200 meters. For the subsequent 30 meters, he evaluated his body’s response. Harris was poised and lucid, but more importantly, he noticed that his usual hand tremors at this depth, a symptom of high-pressure nervous syndrome, were absent. In contrast, Challen, his diving companion who was using helium, showed distinct hand quivering.