The aim of the Watching series is to draw attention to some of the very interesting items around us, things that perhaps we don't notice as much as we might. The first was Bridge Watching, and when this was put ''on the Net'' it produced, to the surprise of the author, such a pleasant flood of e-mail that another was written, called Water Watching. This, too, was kindly received. So it was tempting to continue with the theme. Water watchers enjoy this pleasurable pastime, whatever their educational background; but more knowledge of what to look for will, it is hoped, lead to even more satisfaction. The intention is to encourage interest in looking at water or watery fluids, which are all around us. You don't need any equipment, licences or permits, nor any special qualifications, other than some curiosity, a sense of wonder. The treatment won't be too technical, but hopes to show you how some natural laws control the behaviour and appearance of water. Some knowledge of this can make water so much more fascinating, wherever you see it. There is a great variety of surface water to be seen, waterfalls, streams, rivers, puddles, and lakes; there is rain, snow, hail, frost and dew, as well. The total amount of water on our planet doesn't change. It just goes round and round, in its passage sustaining life in all its forms. Water-watchers can look at it during the different stages of its cyclic tour. So, besides enabling every living thing to exist, water provides free intriguing entertainment, to charm us with its magic. We can all take advantage of it.