The Cold Truth

By Julianna Wallingford

At an altitude of nearly nine thousand feet, the water in Grand Lake, Colorado, on the western border of Rocky Mountain National Park, is never balmy. The morning sun had brought the air temperature to nearly 80°F, and the surface water temperature to 58°F, but there was no question that we would be wearing drysuits, hoods and gloves.
My dive buddy and I had driven up from Boulder to explore a sheer rock wall that forms one border of the east side of the lake. Since we had made our most recent dives in the warm waters off the Florida Keys, it took a little adjustment to get into cold water gear. We then made a precarious trip over slippery rocks to the water. After checking my buoyancy, I discovered I was a little light, but not enough to justify repeating the trek over those rocks. I could descend by using the time-tested diving technique of “thinking heavy.”
I am accustomed to the poor visibility associated with silt-bottomed lakes,
but I had never before seen the light absorbed as quickly as it was in
that high mountain lake. At 15 feet,
I had lost the ability to distinguish
the color of my dive buddy’s bright neon drysuit.
We descended along the contour of a deep, hard mud slope, the flashlight showing us only a ripple pattern of the mud and an occasional golfball. Once the light revealed the familiar shape of a coke bottle, and I stuffed it in the pocket of my BC, as a reminder of a nondescript dive.
The slope intersected with the rock wall at a depth of 75 feet. My buddy hugged her arms across her chest to indicate that even a drysuit wasn’t keeping her warm in 36°F water. We had only been submerged for 15 minutes. At that altitude, in those conditions, it was time to head up for comfort as well as safety’s sake.
As I nodded my agreement to ascend, a blast of bubbles pounded into my mask, and the inside of my mouth became an Arctic zone. My valve had frozen open. I discarded the free-flowing regulator and placed my secondary regulator in my mouth.
Then I learned a cold truth: at 70 feet, with a free-flowing regulator, my first stage was unable to provide enough pressure for my alternate air source to function.
My dive buddy was already handing me her alternate, but to her surprise, I refused it. Another lesson in physics was being revealed: a tank that is being emptied by a free-flowing regulator quickly becomes positively buoyant. Since my buoyancy had been marginal to start with, I did not want to take my buddy on a ride to the surface.
Holding my regulator in my mouth with my left hand and trying to vent my drysuit with my right, an awkward position at best, I made a sincere but inefficient effort to control the rate of my ascent. The frigid bubbles buffeting my head were freezing my face and filling my hood to Pillsbury Dough Boy proportions.
With my own fins flared, and my dive buddy grasping my ankle with her fins flared, we managed to extend our trip up the wall for nearly two minutes. Under normal circumstances, I would have preferred an ascent time closer to three minutes, plus a safety stop, but considering the pounding my head was taking, I was actually grateful the elevator ride hadn’t taken longer.
It was a long trip home with the car’s heater blasting hot air, slowly raising my body temperature back to normal. Sitting back with my eyes closed, nursing a raging headache, I reviewed the dive.
It had been disturbing to learn that my first stage was unable to provide an adequate airflow to my alternate regulator when my primary was free-flowing. Had I had a redundant system, the incident would have been a non-event. Simply turning off the primary system and breathing from an alternate air source would have allowed me a slow, comfortable ascent.
Even a small Spare Air would have made it possible to rise to a depth at which my secondary regulator would have received enough pressure to function. Without a constant cascade of supercooled air flowing through it, the primary regulator might even have thawed on the way up.
My problem was magnified by the fact that I was slightly
under-weighted.
I was lucky. I ended up with nothing worse than a bad headache and a cold body. On the positive side, I gained a new respect for the speed with which one problem compounds another, and a 1938 Coke bottle for my trophy shelf.