Ok, so it doesn’t really need to be said, but I’m going to say it anyway. You do this at your own risk. Smartphones come with varying degrees of water resistance, so if you fry your phone, it’s your own fault.
With that said, the guys from COOPH show a quick tip in this video to make a waterproof housing for your phone using items you probably already own. All you need is a glass dish with an airtight lid and some gaffer tape!