Reversing Rapids

I visited the reveresing rapids in St. John, NB, yesterdy. This picture was taken at low tide when the the water from the St. John River was flowing from right to left into the Bay of Fundy. Six hours later I went back for high tide and the water from the Bay of Fundy was pushing the St. John River "upstream" and the rapids were reversed. At "slack time" between high and low tide, the water is calm. At low tide as shown, there are about 10 million gallons of water per minute flowing through this channel.
Warmest regards, Gus