One of the most accessible rides for cyclists of all skill levels is the Great Lakes Waterfront Trail and Long Sault Parkway between Upper Canada Village and Cornwall, Ontario in Canada.
The Waterfront Trail in this section is completely paved, and relatively flat, because a lot of the trail runs along a former railway line. Long Sault Parkway is also relatively flat and the views you have as you hop from island to island are breathtaking.
There's a lot to see if you come out to ride in the area, including abandoned roads (including abandoned sections of Highway 2, which was lost due to flooding of the St. Lawrence River in 1958, Upper Canada Village, which has historic buildings saved from the flooding and even a museum dedicated to the lost villages along the river.
This was an amazing ride and it's one of my favourites!