The NWT's Great Slave is a big lake with a deep secret:
Beneath its whitecaps lies a mysterious, watery abyss unrivaled in North America. At a point not far offshore from the community of Łutselk'e on Christie Bay the lake-bottom falls away two-thirds of a kilometre, making it the deepest lake in North America and the sixth deepest on Earth. Put in context, Great Slave could sink the CN Tower. To drop an anchor to the bottom, a fisherman would need more rope than he could lift.
According to John Ketchum of the Northwest Territories Geoscience Centre, there are debates about what's behind Great Slave's great depth. Some have said it's an ancient rift, like the famous tectonic ruptures in East Africa. Others say it was caused by glaciers eroding the brittle rock along an ancient geologic fault.
Also unclear is precisely how far down it goes. The official figure is 614 metres – 2,014 feet. But according to University of California researcher Slawek Tulaczyk, who conducted bathymetric soundings in Christie Bay in 2005 and 2006, there are trenches that reach even farther down, by as much as 30 metres.
It isn't an environment a person would want to visit. At those depths, sunlight doesn't penetrate, so all is perpetually black. Even worse, the pressure is stupendous – around 800 pounds per square inch, or 1,000 tonnes on the average-sized human body. You wouldn't last long down there – so maybe its best that Great Slave keeps its secrets.