I use a tripod for almost all of my shots, Sue. For my waterfalls it's essential, especially since they're typically shot in portrait mode, which makes a beanbag or a monopod virtually useless. Because I spend so much time hiking, I got a Gitzo Traveller, which is both light and small. It folds up to 15.4" (39 cm) and weighs only 2 lbs (0.9 kg), not much more than a bottle of water.

And of course I agree with everything Danny says, especially the last paragraph. The heavier your equipment, the harder it is to handhold, and vice versa.

Dennis