Mere moments after Canadian canoeist and explorer Adam Shoalts realized he had just discovered a completely uncharted waterfall in northern Ontario, he made another realization: he was about to be swept over the water's edge.

Shoalts and his canoe fell 12 metres over the falls, before becoming trapped under water below the falls for what he remembers as “a long time.” Somehow, the experienced outdoorsman was able to swim to the surface and gather up his banged-up canoe and most of his gear. Then, after taking a few notes in his log, Shoalts simply got back into his boat and made his way on down the river.

Over the next several days, the Fenwick, Ont. native went on to discover six more never-recorded-before waterfalls, an achievement that’s relatively unheard of these days.

That was one year ago. This week, backed by the Royal Canadian Geographical Society, Shoalts is headed back to the Again River, to retrace his path and make more detailed recordings of what he discovered.

In the age of Google Maps, satellite imagery and aerial photography, one would think that every river and creek in the world had already been dotted out. But in fact, Shoalts says, that’s not the case. There are still vast areas of northern Canada that are mostly a mystery to geographers. So it’s not every day that one gets to help make seven new discoveries that requires cartographers to redraw their charts.

“It’s pretty rare in the 21st century to be doing these sorts of expeditions that result in actual changes to the map,” Shoalts told CTV’s Canada AM Thursday. “It’s something we associate more with the past than the 21st century.”

Shoalts has been fascinated for several years with an area of Canada’s North known as the Hudson Bay Lowlands. It’s the country’s largest wetland -- and the third largest in the world – and contains thousands of waterways that were never properly mapped by early European and Canadian explorers.

He became particularly interested in the Again River, a 100-kilometre tributary straddling the Northern Ontario-Quebec border that was likely too rocky for fur traders or aboriginal populations to ever spend much time on.

Shoalts knew from satellite imagery and aerial photos that the river had a lot of whitewater rapids. But he says there was no way of knowing whether there were any waterfalls without seeing it first-hand.

So last summer, he decided to head out to the river’s headwaters about 200 km northeast of Cochrane, Ont., and paddle his way downriver solo, becoming the first person on record to traverse the river’s length.

“I went there with the objective of exploring the river. But never did I dream that I was going to find seven waterfalls on it,” he says.

The first waterfall he found, around the ninth day of his expedition, was the big one that almost took his life.

“It was a cold, rainy day. My teeth were chattering, I was shivering, so I was getting a bit impatient and starting to take risks I normally wouldn’t have taken,” he remembers.

As he paddled along he noticed that the current was getting stronger and the rapids were getting bit bigger.

“I continued to run them and figured it was nothing I couldn’t handle. And then the next thing I knew, I could hear this real ominous roar coming up from down river,” he says.

Through the mist, he could see that the river up ahead appeared to just disappear in front of him. It was at that moment, he realized he had discovered a previously unknown waterfall.

In the next moment, he realized he was not going to be able to back-paddle out of there. So he pivoted his canoe sharply sideways and braced himself for what would be a 12-metre fall.

“I went straight over and got sucked down beneath the waterfall,” he says.

When he finally made it to shore, Shoalts took recording of his coordinates. The latitude and longitude of the six other waterfalls were also recorded and submitted in a report to the Royal Canadian Geographical Society, which is adding the water features to the correct topographical maps.

Shoalts says he might one day submit the paperwork needed to help name the waterfalls. But for now, his focus is on his mission that begins this week.

He will return to the Again River to take the time to photograph each waterfall; measure their height, and plot them more precisely on the map. He’ll also make some more detailed observations about the area, noting flora and fauna along the river and other geographic features.

And this time, when he reaches a waterfall, he’ll know it's coming.