Tidal Bore

The word came from an old Norse word, "bara" meaning "a wave". The wave is formed from the incoming tide opposing the outward flow of a river or bay. A wall of water is formed where the two opposing flows meet by this wall of water forms a wave or multiple waves as it pushes its way up the river. The highest wave is measured at 17 m tall.  It pushes water as far as 48 km inland and has reached heights of 5 to 10 feet