Overall great
I have used this case for over a year and a half to swim laps and I love it. Each time I use it I swim for over a mile freestyle, so yes it works for an active swimmer with their head fully in the water. The headphones are not perfect, you will sometimes get air pockets which makes the sound go in and out a little when you turn your head, but overall they work. I am able to listen to tunes while swimming laps, same as if I was running. The arm sleeve is the only disapointment, it does not adjust small enough for my arm (I'm small but not that small and it would have to adjust 2 inches smaller - only a massive body builder could use the arm sleeve). I just clip the case on the back of my suit and it works, but I would like to have the armband work.