The Again River cuts through the hard Canadian Shield of Northern Ontario and runs north, into Quebec and back again, to meet the Harricanaw River before emptying into James Bay. It’s an unwelcoming, shallow waterway, replete with clouds of bloodthirsty insects, dodgy rapids, narrow canyons and still-unmapped waterfalls. Explorer Adam Shoalts discovered the latter the hard way when his canoe plunged over the edge of a 12-metre waterfall in August 2012. He survived, still managing to become the first known person to canoe the river in its roughly 100-kilometre entirety. Now he’s going back. His plan? To be the first to map the area’s waterfalls.

He won’t, however, be the first to map the river’s course. Aerial photography of the area was captured for that purpose in 1947 by the RCAF. One small team of geologists from Quebec’s Departement des Mines et Ressources Naturel used those images while exploring parts of the Again River and surrounding area in 1961, on both the Quebec and Ontario sides — though they were lucky enough not to come across any major waterfalls.

Jack Gunn of Saltspring Island, B.C., was the junior man on that two-person crew in 1961, along with senior geologist Gwilym Roberts. Gunn was just 19 at the time, a McGill University geology student on a summer job. “Because I’d done some bush work before then I was basically there to keep Gwilym alive and bring him back. He didn’t really like the canoe,” he laughs. “I was the gofer. I managed the canoe, the camp, did the cooking and a little bit of fishing. And I kept radio contact with the base camp, which was important, although the radio only worked properly about once a week.” Each night they camped alongside the river, then canoed downstream another 10 or 15 kilometres and set up camp again, before heading off into the muskeg to locate geological outcrops.

“We saw a lot of rapids and smaller waterfalls along that section of the Again, but not the 12-metre waterfall that Adam Shoalts went over,” Gunn says. “We were helicopter supported, so it could have been that we were dropped well below those waterfalls deliberately.” He’s unsure about where on the Again River he and his geologist began more than 50 years ago, but it took them several weeks to reach its confluence with the Harricanaw River.

Shoalts is eager to pore over the survey reports Gunn’s team produced. “Exploration has always been about documentation — filling in gaps of knowledge, building off previous generations of explorers and leaving records for future explorers,” says Shoalts. “And this is precisely what the objective of my expedition is: to document, photograph, measure and map the waterfalls of the Again River. Generating new geographical knowledge is the very essence of exploration.”