David Ashdown was in Beijing covering the 2008 Olympic Games
Diving is a very very fast moving event. It's not the speed that they are dropping, it's the twisting and turning, which require a very fast shutter speed to stop the movement. I tried 1/1000 but there was a lot of movement on their heads as they spun - the Chinese diver Liang Huo had longish hair that was still quite wet before he dived off, so as he spun (and if the shutter speed was high enough - at least 1/2000 second) the water would form a circle away from him. What is also needed is a dark background to highlight the spray.
I was almost at pool level looking up at the 10m board because what's behind him is the top of the seating and also the darkest place in the pool. It looks like I'm level with him as that's the effect that a very long lens can give, a loss of perspective of height. What is also needed if a few old darkroom skills, using photoshop to raise the contrast and darken the background to enhance the water, to bring out the best elements of the picture. And hopefully make people thing how did he take that picture, well that's how!
Picture taken on a Nikon D3, 500mm lens, aperture F4.0, 1/2000th of a second