WE'VE BEEN OUT for just over two weeks, our exploration of Peel's inner reaches—the North Arm, which extends ten miles north of Tilman Island to within 13 miles of Argentina, and Calvo Fjord, which runs eight miles to the east—funded by a Gore-Tex Shipton-Tilman Grant. Even though cruise ships work the main stem and visit Calvo's first two glaciers, a mile or so in, the rest of Calvo and the North Arm goes unseen: The North Arm is blocked by icy narrows, while Calvo's extremities are so frozen that it would take an icebreaker to progress more than a few miles. Reg and I made it six miles up Calvo but have gotten stuck on the way out. The wind has shifted, packing the ice around and ahead of us. We muscle the boats in reverse and paddle until dark, landing on a gravel beach.

We leave our drysuits on (wearing is the only reliable method for drying anything) and set up camp.

"Cook in the vestibule tonight?" I ask. It's raining harder again.

"Makes sense," says Reg.

"Chicken Polynesian or chicken à la king?"

"Polynesian." He's left the higher-octane 2,500-calorie meal for me, even though we're both exhausted. Soon, the only sounds are slurping and rain. I take a mugful of wine and heat some water bottles to warm our sleeping bags.

Our misadventure takes place in a rather auspicious spot, given the name of our expedition grant. In 1956, British explorer H.W. Tilman sailed his wooden cutter Mischief up Calvo Fjord to launch the first crossing of the Patagonian ice cap. "Peel penetrated furthest east so that the crossing would be the shorter," he wrote, "and it contained no less than ten glaciers which reached the water as well as several others which came within a mile of shore." But the Mischief was able to reach land only at Calvo's first glacier, very near where Reg and I got stuck.

Tilman launched his crossing from this less-than-ideal spot. From above, he looked down on Calvo. He would later write, "It appeared so narrow and so choked with ice, that we were glad we had ignored it." But while Tilman and the men explored the ice cap, stopping several times a day to brew tea, the ship's crew tried to navigate the shallow pass to the North Arm and damaged the Mischief's keel, nearly sinking her. They made it out successfully, but 20 years later Tilman was lost at sea off the Falklands. The island that guards the North Arm's choked entrance now bears his name.

Reg keeps track of these sorts of things. He's a sponge for old nautical information and has paddled and guided more of Chile's 4,000-mile coastline than anyone. And nothing beyond local fishermen's speculation showed that anyone had ever before been through the narrows to the end of Peel's North Arm.

Reg is a contemporary of a band of California adventurers that includes Patagonia founder Yvon Chouinard, The North Face founder Doug Tompkins, and big-wall legend Royal Robbins. The three climbed together in Yosemite in the sixties; in the seventies, they turned from rock to water, exploring California's steep creeks and waterfalls. And if you wanted to run hard whitewater, Reg was the guy you called.

Among them, the four notched first descents on now classic runs like the Upper Kern, flowing off Mount Whitney, and the Middle Fork of the Kings, through Kings Canyon National Park. In 1980, they ran the Devils Postpile section of the San Joaquin, which features an unscoutable, unportageable Class V gorge called the Crucible that's still feared even by the best young kayakers. Reg was the "probe" for that line. "I've got a lot of respect for that guy," says expedition paddler Ben Stookesberry, 29. "He's a complete badass."

While the others went on to found successful clothing companies based on the dirtbag image, Reg stayed in his boat, albeit reinvented as a sea kayaker because of slowing reflexes.

"I'm finally living the life I knew was out there," says Reg with the vigor of an 18-year-old raft guide. Most winters since 1991, he's returned to Chile; this year, for his second attempt on Peel, he invited me. He figures that, with a month's worth of food crammed in our hatches, we'll be able to wait out the ever-changing ice floes and unfavorable weather that turned him back in 2004.