Our goal was a site called Shangri-La, but we found the entry for another spot—charmingly known as Stairway to Hell—much more inviting. The shoreline had that September look about it, a few tentative reds and oranges in the trees, sunbeams pushing through to the water in dramatic shafts. We dropped to a hundred feet where visibility promptly gave out; with lights blazing we could see perhaps a body length in front of us, which is not so much diving as groping in wet darkness. Happily, the shallows more than made up for it: sunlit plateaus, little gullies dropping away like miniature canyons, and clouds of bluegill and rock bass drifting about in the beams of light. I managed a photograph of a pike with a shaft of sunshine pouring down behind him—pure National Geographic, if you squint and have had two martinis.

Of course, SCUBA is never content to let you bask in simple pleasure. Heather surfaced with her rebreather gurgling like a blocked drain, which turned out to be a cracked bailout valve. The manufacturer had discontinued the part precisely because it tended to do this sort of thing, which is rather like Ford announcing they’ve discontinued brakes on the Focus because they stop working. The whole unit was nearly brand new, maybe thirty dives on it, and is now the BOV is but an expensive paperweight unless the company takes pity and offers her a replacement.

Later in the week, I returned to Gooseberry Falls, partly because the weather was perfect and partly because, having seen a sturgeon once, I was helplessly obsessed with the notion of seeing one again. I crept out to the sand flats at fifty feet, laid myself on the bottom, and became as inert as possible. On a rebreather you are virtually silent, and the idea was to let the lake forget I was there. For twenty minutes nothing happened. Then—like a Zeppelin gliding out of the gloom—there he was. A sturgeon, as improbable as a dinosaur, headed straight for me. I made the catastrophic mistake of flicking on my video lights, and he wheeled away in an instant, gone like smoke. The footage is terrible, but the sighting itself is now my favorite boast, doubly so as every seasoned diver I know insists they’ve never seen one in decades of Superior diving.

When Superior grew cranky again, we steered north to the St. James Pit in Aurora. This is another of those places where the landscape is half natural, half industrial relic: an old iron pit that has since filled to a depth of nearly 400 feet and is now used as a municipal water source, trout fishery, and, improbably, dive site. The bottom is littered with curiosities. Heather, diving on open circuit thanks to her wounded rebreather, dropped past 170 feet and reported finding a skid steer sitting there in the gloom. How a piece of heavy construction machinery ends up there is anyone’s guess, though one suspects alcohol and poor judgment were involved. I stayed closer to the hundred-foot contour, drifting along the wall, before wandering back to the shallows where the light filtered in and a few indifferent trout kept me company.

Evenings were spent, as ever, in the garage, patching small betrayals in my drysuit and wondering if the leak this time was in the patch or in my imagination. The days ahead look promising on the weather forecast, which means there will be more pits, more light streaming through the water, and undoubtedly more gear that decides to express its dissatisfaction at the least convenient moment. Still, when you’re floating in a shaft of sunlight among bluegill in a mine once carved out by men and now reclaimed by fish, it feels like a fair trade.