We set off along the Two Harbors break wall, a long pile of riprap rocks that serves primarily as a barrier against Lake Superior’s frequent mood swings. As dive sites go, it is not exactly the Great Barrier Reef. Occasionally, if you are very lucky, you might spot a sculpin—an odd little fish about the size of a candy bar that looks like it once lost a bet with evolution. There are also the occasional opossum shrimp, which, despite the intriguing name, are really just small, nondescript lake creatures with little interest in being observed. Otherwise, the experience is mostly a slow, meditative descent into the vast and empty blue.

On the swim out, I noticed my right hand felt warmer than my left. Not dramatically so—no sudden urge to remove my glove and wave it about triumphantly—but enough that I felt a small flicker of hope for my experiment. We continued past a particularly bizarre underwater landmark known as the “Garden of Skulls,” a collection of carefully arranged rock circles, each one smaller than the last, culminating in a four-foot post upon which some enterprising diver had impaled a deer skull. It is both eerie and oddly artistic, though mostly it serves as proof that divers, when left to their own devices, will create increasingly strange ways to entertain themselves.

After about 30 minutes, it became clear that it was time to turn back. I wasn’t shivering, but I was cold enough to know that if I wanted to retain any meaningful use of my hands at the surface, I should probably start heading for shore. It was also around this time that I noticed a slight flaw in my experiment—both of my hands were now uncomfortably numb. If I really concentrated, perhaps my right hand was marginally warmer, but not in any way that suggested success. It was a bit like realizing that, yes, one foot is technically drier than the other after stepping into a puddle.

On the way back, Heather, who possesses an inexplicable fondness for squeezing herself into submerged rock crevices, discovered a small opening in the break wall. Naturally, the cave diver in her could not resist. I watched as she disappeared into the gap, shaking my head in the manner of someone who knows better than to ask why. Circling around, I managed to snap a few photos as she emerged, with a hint of a smile as reconnected with her inner cave diver.

From there, it was another 15-minute swim back to shore, where I surfaced with two very cold hands. My hypothesis, as it turns out, was completely wrong—but at least it only cost me a $10 wrist seal. And, of course, a little bit of feeling in my fingers.