Mary Ann Falls is a popular hike in Cape Breton Highlands National Park that rewards hikers with a gorgeous 20 ft waterfall. Great in late spring, summer, and fall, but if you hike here in the summer you can go for a refreshing dip in the chilly water. The hike is challenging, with lots of ups and downs (1,181ft elevation change) over the 4 miles (6.5 km) out and back trail. but it's a beautiful waterfall!