The 4 factors that have led to a 'golden age' of discovery for Great Lakes shipwrecks

There's never been a better time to find, explore and document shipwrecks on the Great Lakes, thanks to a combination of technology, environmental change and surge in public interest, according to those who uncover the sunken history of the world's largest lakes. 

The University of Buffalo estimates more than 6,000 shipwrecks are on the bottom of North America's five Great Lakes, which, since the late 1600s, have been lost in wars, accidents, or frequent and powerful storms.

In the last 18 months, three previously unknown Great Lakes shipwrecks have made headlines around the world, from the steel bulk freighter Huronton, the 19th-century cargo steamer Africa, and in February, the Second World War-era freighter Arlington.

Explorers say the pace of new discoveries has quickened, thanks to new technologies, climate change, invasive species and a surge in public interest. 

"I've lived at the most fortunate time possible for being an underwater explorer because of the developments in technology," said Jill Heinreth, a full-time underwater explorer and explorer-in-residence for the Royal Canadian Geographical Society.

She said cameras, drones, underwater scooters, even breathing apparatus have all improved, and in many cases have become cheaper, over her 30-year diving career, during which she's documented everything from underwater caves to ghostly shipwrecks. 

"We've gone from just using a single scuba tank on our backs to using something that's much more akin to what an astronaut wears for a space walk," Heinreth said. "It's called a rebreather and it increases our range, our time and our depth capabilities by recycling our exhaled breath."

Underwater drones in particular have led to a number of shipwreck discoveries. Most recently, the Africa was found in Lake Huron by a husband and wife team while filming the upcoming TVO documentary All Too Clear: Beneath the Surface of the Great Lakes. 

This winter saw the lowest level of ice ever recorded on the Great Lakes. It's meant lower lake levels and higher rates of erosion along sandy bluffs, devastating coastlines and, in some cases, uncovering lost pieces of history. 

Durrell Martin, president of Save Ontario Shipwrecks, told CBC's Afternoon Drive on Friday that the shifting coastlines have unearthed a number of discoveries, including a 600-year-old dugout canoe in Salmon Trout Lake, a small inland lake about a 20-minute drive north of Bancroft. 

"This came due to frost heaves and erosion from increased run-off of water," he said. "This is about halfway between Peterborough and Ottawa, and the Ontario Marine Heritage Committee has been documenting this unusual find of Canada's pre-colonial history."

Martin said more discoveries are likely to be made this spring as communities around the Great Lakes experience increased erosion along their shores, caused by a lack of ice on the lakes. 

The introduction of invasive zebra and quagga mussels from Europe through the ballast tanks of freighters on the Great Lakes has made the murky turquoise waters of the Great Lakes crystal clear. 

"In the early days, I once literally ran face first into a ship I couldn't see in front of me," Martin said. "Now I can see 200 feet in front of me.