Maligne Canyon is one of my favourite places to visit in Jasper National Park. It is just minutes away from the highway. At the time of writing, it is currently closed due to wildfire damage but may still reopen in time for the summer season (check updates on the Parks Canada website). Photos above were taken pre-wildfire.
When it was last open, there was a choice of loop and out-and-back routes through the canyon, all featuring impressive views of the rushing water and rock formations.
The easiest was a very short 600m loop to Bridge #2. For a longer experience, I would always recommended the hilly 5km out-and-back route to Bridge #5. It includes numerous viewpoints and even several waterfalls. There is a loop alternative but it's less scenic as the path veers away from the canyon.
A Parks Canada parks pass is required to explore Jasper National Park ($22/day for a vehicle of up to 7 people).