When I was in Oahu a few weeks ago I was shooting a bit of photography like this. Super close to the water as it splashes up against the sand or surrounding rocks. It's actually not the smartest thing to do with an expensive Sony A7r and after a few very close encounters I decided it was enough. But not before I got a few cool shots!
I did actually ended up with a grain of sand in one of the little wheels that took me a few days to finally grind out.