You are allowed to carry a gun in a national park....
In general not in Canada. There are exceptions for hunting permits where allowed and (as of 2011) for guides in polar bear country.
http://laws-lois.justice.gc.ca/eng/regulations/SOR-81-401/page-2.html#h-9
http://www.pc.gc.ca/eng/nature/~/me...orizedtocarryanduseafirearmforprotection.ashx

