I'd stay away from a store-purchased boom-box. My friends and I have been floating the guadalupe for 6 years. Our first radio we tried was a sony "water-resistant" model that we purchased at Best Buy. I don't even know why they bothered putting "water-resistant" on the label. While floating, we came up to a small dip in the river. My friend was holding the radio on his lap, one splash and the radio was KO'd. We tried to have it repaired, but it was a done deal. And of course our warranty didn't cover water damage. How ironic is that? Since then we've been making our own. You can find tutorials all over the internet, they aren't too difficult to make if you have any knowledge of car/marine audio. We actually just started marketing our coolers for sale online. Feel free to take a look, should give you some ideas as to what you can create with a little ingenuity. I don't have enough points to post a link, but i'm sure you can google AquaticAudio and find us.