I think the visit to the White Water Walk (formerly called the Great Gorge Adventure) is underrated. It is located a few kilometres downstream and usually less busy than the other attractions. The elevator ride down to the dark and cool tunnel is as much fun for the kids as the one at upstream Journey Behind the Falls. It leads you to a boardwalk where the river is 38 metres deep, making the water gush down in impressive swirls at the speed of over 60 km/hour. On our last visit with four visiting cousins, our 15-minute walk on the boardwalk was beautiful, safe and refreshing, without soaking us, and the kids enjoyed climbing up the giant boulders.