Marilyn in Canoe, 1953
This earlier thread from the WCHA forums has another pic of Marilyn posing with a Mountie. The conclusion was that these pics were taken in Banff as while she was filming River of No Return.
Marilyn with a Mountie, 1953
It also happens that this isn't the first time Marilyn was filmed paddlng. An obscure 1947 film called Scudda Hoo! Scudda Hay!, featured scenes of Marilyn and another hollywood hopeful paddling a canoe. The following stills were found on this Monroe Fan Site. If you're a fan of Marilyn and Wooden canoes, these photos are sheer joy...
October 2016 Update: For a colour version of Marilyn paddling in Banff, go to this post here.