We have three major parties that cover most of the country and a few middling regional ones. So, it's analogous to claiming the tallest person in a group of three is the tallest in the world.
As far as the NDP go, they're not even far left for Canada.
See; Animal Protection Party of Canada, Communist Party of Canada, Marxist-Leninist Party of Canada, Marijuana Party of Canada, Parti Libre Canada (Those are of the ones that still have valid registration with Elections Canada).
Also, if the NDP are "far left" in Canada, who is just left of centre?