Lake Minniwanka is a beautiful lake connected to Two Jack Lake (a popular camping location) inside Banff National Park, and right outside the City of Banff itself. This lake is massive!!! But a sight to see. In the summer there is a 30km walk around the lake, there also boat rentals available!
If your planning on paddle boarding or kayaking, you might want to try Two Jack lake, its a little narrower so less chance of hitting an unpredictable wind storm!
This area is one of the few places in any national park where there are over flow camping! A little known jem to some, although there is no power hook ups, and not really any bathrooms (so basically back country camping) its a handy tip to remember if you run into full campgrounds over and over. Which is a likely scenario in the prime summer months!