For these gift ideas, just add water.
The idea of listening to music while swimming laps sounds ideal, but the actual execution is tricky. H20 Audio has a solution with these truly custom headphones and waterproof MP3 player. To get an accurate headphone fit, the company recommends ear impressions taken by a local audiologist (usually costing an additional $50 or so). The audio player itself provides over 10 hours of play time and the ability to stream from a smartphone.