The combination of mild activity and major anxiety causes my core temperature to rise to 100.3. A boatswain's mate hands me a life jacket and ties a rope to it in case he has to yank me out of the water. Steinman gives me the nod, and I kneel down to enter the ocean. The water temperature hovers around 60°F. This may not seem that cold, but remember: Water is 25 times more efficient at sucking heat from the body than air. For posterity, here's a step-by-step account of what happens when you're stuck in the drink.
Chillin' Out: 9:30-9:32 a.m. The instant I enter the water, the cold shock triggers an involuntary gasping for breath. Try as I might, I can't seem to take in or hold a decent lung of air. This is called "truncal immersion reflex"-a phenomenon now believed to be the root cause of sudden drowning syndrome.
"If your head is underwater and you gasp and hyperventilate," Steinman explains from his perch on the dock, "you're not going to make it." Thank goodness for life jackets.
Dr. Gordon Giesbrecht, a Canadian hypothermia researcher, once had volunteers hold their breath on land and then upon entering cold water. People on land averaged 70 seconds, but in 50-degree water, only 25 seconds.
Besides the effect on respiration, my skin stings. I hardly notice the surge of adrenaline that temporarily escalates my heart rate and blood pressure. My body has begun to mount a hypothermic defense-a response honed by evolution to retard heat loss. Paradoxically, the initial cold shock begins to wear off after only a minute. I start breathing normally, my skin stops stinging, and I feel almost comfortable-the cold has become an anesthetic.
Icy Hot: 9:32-9:44 a.m. That numbness, alas, proves short-lived. My hands and feet now prickle with painful pins and needles-evidence, says Steinman, that my peripheral blood vessels are constricting in an effort to shunt warm blood from my extremeties to my vital internal organs. "Pretty soon," he explains, "your hands and feet will be nearly the same temperature as the surrounding water."
By 9:36, his prediction comes true. A Coastie asks me to wriggle my now blanched fingers and thumbs in sequence, which proves surprisingly difficult. "This loss of manual dexterity is a real problem in survival situations," says Steinman. "When the muscles and nerves get cold enough, it's virtually impossible to activate a flare or work a radio."
By the 10-minute mark, I'm confident my time in the drink is drawing to a close. "So what's my temperature now?" I ask.