One of the best bets for a longer, seamless canal-side run in Groningen is a route just east of the city, combining the Roeierspad & Eemskanaal paths. Up to 12.8 km of flat, uninterrupted waterside running!
This route can also be accessed from the center of Groningen — just over the Steentilbrug, [BURG=BRIDGE] take the the northern path along the Eems Canal (Eemskanaal Noordzijde) for 2.5 km, passing the Berlagebrug, around the marina, crossing the Oostersluisbrug Zuid bridge on the Roeierspad path, and head east. After ~3 km, the path turns into the Eemskanaal Noordzijde again, continuing east for another 7.3 km to Woltersum. Nice water views the whole way. Can get a bit monotonous…but great opportunity to do some intervals or rack up some miles!
Note: Can also start on the Roeierspad, eliminating the 2.5 km downtown access portion.