Thank you, Francois.
In person, the water looked much darker, without the foamy appearance. When I got home, I was surprised to see how the picture was recorded by the camera. I took the picture handheld around noon, with a 1/400s shutter speed, so the whitish appearance was not due to motion blur. Must have been the angle of light. 3 hours later, I took there another picture, this time with water surface looking much more naturally.