Reversing Falls of Saint John

Reversing Falls of Saint John, natural wonder at the mouth of the St. John River in Saint John, New Brunswick, Canada. High tide in the Bay of Fundy at the river's mouth forces the water's current to flow backward over the falls, a 14-ft (3.7-m) drop in the river's elevation. During low tide, the river flows over the falls through a narrow gorge into the bay. But at high tide, when the water in the bay reaches its maximum level, a rushing tide (bore) sweeps in and raises the level of the river to the exact height of the drop. The rush of water backward over the falls gives the site its name.