Warm down or cool down, whatever you call it, with championship meets coming up, it's very important that swimmers understand the importance of completing it. Why do it: Warming down is an easy exercise that will allow the body to gradually transition from a working state to a near resting state. Smooth slow swimming after an intense race allows a gradual decline in heart rate that reduces stress on the heart. It feels good too. How to do it: 1) During the demands of intense speed training, or racing, the body is put in extreme stress... which it should be. 2) As soon after the intense race, swimmers should spend as much time as necessary swimming slow, smooth, long strokes to allow the body to recover. 3) This slow swimming can also aid in the return of "feel" to the stroke. 4) Stretching is also a good form of the cool down process, but stretching can also be done IN the water during your post race swim. Long streamlines off the wall, long strokes, taking your time can also help. How to do it really well (the fine points): Simply put... finish it. Most swimmers think a couple hundred yards of swimming after an intense race is enough. They put a yardage limit on how long they're going to swim rather than swimming until they feel the race is behind them. Sometimes a proper warm down can take 20 to 30 minutes... nearly as long as the warm up did. Don't rush it, and don't limit it by a specific distance. Feel it, and it's generally better to go a bit longer than a bit less.