Or maybe it's just the people who comment on its gyrations. A Reuters piece from today is a case in point:
Loonie slips on US economic outlook: The Canadian dollar slid lower against the U.S. dollar as investors were loath to bet on the currency, given Canada's heavy dependency on the waning U.S. economy...
Yes, the Canadian economy is exposed to the risk of a severe US downturn, so it's reasonable to expect a depreciation against currencies that are better insulated, such as the euro or the yen. But that reasoning also means that the CAD should appreciate against the currencies of economies that are less insulated from a US recession. A good example of an economy that is more exposed than Canada is to a US recession is - wait for it - the US.
Unless someone has a story in which a Canadian slowdown would be even more severe than what will hit the US - and I've yet to see anyone explain how it will - then this story from Reuters makes no sense at all.