“You Can’t Hold Your Breath Very Long at 97 Feet”
How I learned to use the purge button every time

By Richard Black
As Related to me by Kevin Carlisle

I’m proud to call Kevin Carlisle a friend. He’s a kind, genuine, and patient individual who is an experienced and talented cave diver. I’ve always enjoyed time spent in Kevin’s company, either in the caves at Jackson Blue or talking about the dives around the coffee table at Hole in the Wall House.

Kevin has a story he has shared in my presence several times to help other divers. It is about an almost tragic incident that he experienced on a dive when he was at Intro to Cave level. It’s a lesson we all can learn from, whether cave diving or in the open water, and Kevin’s willingness to allow it to be published is greatly appreciated.

Kevin and a buddy planned a cave dive at a favorite location- Jackson Blue on Merritt’s Mill Pond near Marianna, Florida. He geared up with his cave diving buddy in anticipation of a nice dive. There had been no drought and the Mill Pond was full, meaning the water would be deep and there would be a good flow. With between 60 and 70 dives logged at the Cavern level and 25 dives logged at Intro to Cave Level Kevin’s confidence and competence was growing. He was well on his way to becoming an accomplished cave diver. He never expected the experience he was about to have.

As the two friends were gearing up Kevin noticed the cheap low quality backup regulator necklace his friend was using and gave him a little ribbing about it before they made their way to the water. He didn’t anticipate the trouble it would cause him soon.

The divers deployed their primary reel and ran the line to the gold line where they tied off and began their dive down the “chimney” and into the cave with Kevin in the rear. At about 400-500 feet penetration and at a depth of 97 feet, suddenly Kevin’s buddy turned and gave the out of air signal. It was later determined that the buddy’s primary regulator had failed and when he went for his backup it wasn’t there. It had slipped from its necklace and was dangling somewhere below the diver. Caught off-guard, the diver immediately thought of his buddy Kevin and turned to ask for help, a skill they had practiced many times in their “S-Drills.”

The practice paid off and Kevin smoothly and effortlessly donated his primary regulator, grabbed his backup, and made the turn to exit the cave. But this was when things began to go badly.

When Kevin got his backup regulator in his mouth he did what he had always practiced, he exhaled to purge the regulator and took a breath of breathing gas. This time something was terribly wrong. Instead of Nitrox he was inhaling water. Kevin says the next series of events probably occurred over about a 30 second period but seemed like an eternity.

With water going into his lungs he began to cough violently and uncontrollably. He immediately took the regulator out of his mouth, examined it and tried to breathe again. Through his violent coughs it was almost impossible to keep the regulator in his mouth so he held it with his hand knowing that if he lost it there would be no solving this problem.

Kevin’s buddy realized the desperate situation and having located his backup regulator returned Kevin’s primary thinking that would solve the problem. But now the violent coughing and panic was causing Kevin to over breathe his regulators. At this moment Kevin thought that any second he would be taking his last breath.

As thoughts of his family and the cold water around him rushed through his mind Kevin’s training and experience took over. He said, “I grabbed a rock and closed my eyes.” As he allowed his mind to take control of his panic he took two deep breaths and began to regain his composure. In a few moments his coughing ceased and his breathing had slowed to a manageable level. Shaken, the two divers made their way swiftly toward the entrance and exited the cave.

Kevin doesn’t give many details about the post dive debriefing but he did confirm the total failure of his buddy’s primary regulator as the first factor in the situation. Both Kevin’s primary and backup regulators were functioning flawlessly. They both knew the necklace had let them down but they didn’t fully understand the remaining series of events. Still shaken they packed their gear and began the drive home.

On the drive home Kevin picked up his phone and called his cave instructor, hoping to gain some insights. The drive was long and so was the talk as they carefully analyzed the near tragic accident. As the details were examined the instructor asked, “Did you hit your purge button?” and the answer was no. Like many of us, Kevin had gotten into the habit of just exhaling a short breath to purge his regulators. Like most of us, he never had a problem, especially in shallow water as he did his “S-Drills.” But this day there was something different. When he needed to purge he wasn’t at less than two atmospheres of pressure. He was at four. At four atmospheres the gas volume is approximately 25% of the volume on the surface. At 97 feet there simply wasn’t enough gas in his lungs to fully purge the regulator.

As is often the case in diving, Kevin and his buddy’s problems had compounded. Equipment failure is a fact of life and we plan for it with redundancy and thorough training. The first event was the failure of his buddy’s primary. This was a problem they had trained for and they knew how to handle. The second event that caused the situation to escalate was the missing backup regulator. A secure method of attachment would have prevented it from becoming dislodged. Many of us have our necklace secured under our mouthpiece zip tie ensuring a secure attachment.

The act that brought the situation to the danger level was the failure to properly purge the backup regulator. Kevin had a fully functioning regulator with plenty of gas in his cylinders. He exhaled as always, but at the deeper depth his short exhale was not enough. Hundreds of feet from the entrance and nearly a hundred feet deep suddenly not being able to breathe is sure to panic any individual. The event could have easily ended tragically but Kevin was able to regain his composure and keep his presence of mind to think his way through the problem. His training and experience paid off and he learned a valuable lesson that day that he’s happy to share with other divers. Since “you can’t hold your breath very long at 97 feet,” you had better always use the purge button. Kevin says from that day on he always does. Do you?