Here is the adagio movement from Mozart's famous clarinet concerto. As a violinist, I suspect that I would be considered disloyal for favoring a clarinet piece, however I can't help but love the mellow lilting melody of this particular movement.
This is one of the songs in my "swim-P3" player. It's a little MP3 player that you can attach to your goggles and thus provide laps of musical entertainment. Honestly, I don't know where I'd be without that little gadget. I get so bored going back and forth... the "swim-P3" player really helps pass the time when doing laps in the pool. Some people may choose more energetic music to swim by, but I favor the more stately and serene pieces. Helps me get into the rhythm.
Without further ado - Mozart's Clarinet Concerto, the Adagio. Enjoy!