Cycling Around Ottawa. Episode 3. a 25 Km Loop Along Both Rivers.
This is a slightly longer loop, 100% on multiuser paths, that runs mostly parallel to the Rideau River.
With lots of greenery, and several segments that run across a very tupid canopy, the ride along the Rideau River Pathway is one of my favourites. And if you time your ride right, you will enjoy the company a lot of majestic dogs on their morning walks.
The only caveat: crossing the Hartwells Locks can be difficult it your bike is too heavy, and can be time consuming on bright sunny summer days (queues are long!)