Another vote for UE Boom. Sound is pretty good, they're waterproof/resistant, float if dropped in water, great battery life, and damn near indestructible. Mine got knocked off the roof of my dad's F-250 onto the driveway and you can barely tell where it made contact, and it sounds the same. I was amazed.
Also, you can turn it off and on via the app, which is nice so you don't have to walk over to physically turn it on. The app also lets you check battery life and connect several UE Booms together if you need to. I've used that feature a couple of times...1) when we are camping with my dad, I connect his and we can have music all around the campsite without having to turn it up so loud that it annoys the neighbors, and 2) when floating in the lake, we have one on the float and the other on the swim platform.
If I was buying today, I'd get the megaboom, which is a larger speaker than the Boom 3 I have.