Can a Canadian citizen join the marines?

If you first obtain a green card/American citizenship, then yes. Otherwise no. Canada has the best trained soldiers in the world, quantity is lower so they go for quality everytime. I remember finding out that ever soldier in the Canadian Army has the equivalent training as 7+ of our guys, because they had less men to do the same job, they all needed to be proficient in as many skills as possible. First time meeting Canadians for this souther boy, and it impressed the hell out of me.