If I'm reading the CIA Factbook correctly, Canada allegedly has only 636 km of navigable waterways. But the 1738 km Mackenize River is allegedly navigable over its entire length. And the Trent-Severn canal is 386 km and the Rideau canal is 202 km. This doesn't make sense.
I was confused as to why Canada was so low, too. Perhaps it's that the waterways have to be in populated areas? Even with that, it still seems ridiculously low I know, but there must be some caveat with the CIA's system that makes it so.