Water shot with a high shutter speed (1/1600th of a second)
Water shot at a much lower shutter speed (1/30th of a second)
Waterfalls can be challenging to do real justice to. But we've all seen the trick where instead of sharp or slightly blurred water, there's a milky stream of blurred water.
So, how is this done? It's very easy.
Firstly, you'll need a tripod or perhaps a wall or similar to rest your camera on. The camera must not move at all during the shot. If you own a compact camera, you can buy very small, very cheap tripods that can fit in your pocket. To make them higher, just put the tripod on a wall, stone or anything else stationary.
Next, lower your camera's ISO as low as it will go. Most compacts can do this, and all SLRs can.
The idea is to deprive the camera of light, to force a very low shutter speed. If you have a camera where you can adjust the aperture (f-stop), set a very small aperture.
Now mount the camera onto its tripod or whatever you're using, and either use a remote shutter control or set the self timer and take the shot.
The remote or self timer prevents camera shake.
For SLR users, if you're still not getting low enough shutter speeds to create that silky water effect, try putting an ND (Neutral Density) filter over the lens. ND filters are simply neutral grey discs of optical glass that don't change colours at all, but do allow less light in. Or if you have a Polarising filter, use that: it should soak up 2 stops of light, being grey itself.
The slower the water runs, the slower your shutter speed will need to be.
Of course, if the water is still not blurred enough, come back on a dull day!