While swimming in the pool and align the lengths ... Its a little weak with gray "waterproof" "bouchons" (different sizes included) I finally used with the white caps (normal) that do not allow water to pass into the ear if you chose the right size according to the ear canal. One can not be demanding too much about sound quality while swimming, such a walkman helps boost its activity, as in running. It takes time and read the instructions to store which allows it to work properly. Good resistance around the head and does not move while swimming. Fast charging in 3 minutes! Although it is not recommended I think the test at sea.