Try using CorrosionX HD. We have been using it for years to waterproof RC model electronics subject to water, snow... HD proofs against the more aggressive saltwater. Either aerosol or fluid, simply collect enough in a jar to soak the shuffle, remove and let dry for a day. Should work fine in the pool or ocean. I like the added step of filling full of dielectric grease to give even more protection. The swimming application is a bit more dynamic than the occasional dunking of airplane electronics in a lake. What about using a short headphone jack extension cable to be able to keep the connector constantly in the jack and sealed w/grease?
