I would agree about 30 mins by the time you stop, listen to the birds & the river.
The boardwalk is not very long..I will say about 30 min round trip. It is nice to do just before or after diner ;)
If you are visiting Canmore during the summer (2018), weekly ghost walks run during the summer on the weekends and they meander along the boardwalk. The Theatre Canmore website has information about the ghost walks.
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