Waterproof MP3 players are not likely to make an appearance at the Olympics any time soon, but it is likely that most of the competitive swimmers are using waterproof MP3 players during the long, monotonous training. Especially with people today, that have very short attention spans, it is increasingly difficult to swim hundreds of laps every day without going crazy.
The good news is that the waterproof MP3 players available today are very functional and do not get in your way much. They have high capacities so that you can have many hours of music available to you while you swim. Not only that, but they sound much better now than they did just a couple years ago.
The problem for most competitive swimmers is that their coaches will not let them wear waterproof MP3 players. While swim practice can be fairly repetitive, most coaches provide input throughout the practice. These players are best for swimmers that are swimming long distances without any feedback from any other person.
Personally, I swim at the local gym and my competitive days are behind me. Any of the available waterproof MP3 players are great for me to use. I have tried many, but I currently use the latest SwiMP3 model. The bone conduction feature is pretty cool. The sound doesn't actually get transferred through the air or water, which can make for quite murky sound, but rather by conducting the sound through bone vibration to your inner ear. That sounds weird but it really works!
If you do any swimming, especially just swimming laps by yourself, you will definitely want to consider one of the many waterproof MP3 players on the market.