This is something for the surfers

This is nice. It's a video of the surfing at Waimea river in Hawaii USA.
It seems that there is a river that flows into the sea, but that it is blocked for most of the year by waves pushing sand to make a wall that stops the river flowing into the sea.
Then somebody makes a small hole and a channel in this wall, and the millions of litres of river water come flooding out. Ideal for surfing. the music is cool too.