If you put your smart phone in 2 or 3 Ziploc bags you can still use it but its well protected.
Just in case anyone is wondering:
1. You can't place calls while under water. The signal gets lost immediately once the phone is submerged.
2. Its hard to use a touch screen under water because the screen thinks its being pressed everywhere at once.
3. You can play good music underwater and hear it well from anywhere in the pool.