I also swear by the UE Boom (lineage). I have the original UE Boom. The 2 is great. Both are over $100. However, I am toying with getting the UE Roll for my daughter.
This little badboy is waterproof for up to 30 minutes. And it comes with a "floatie" for the speaker for in a pool (for example). And it also has a built in clip for putting it on a backpack.
If you aren't specifically looking for a pool/waterproof focused speaker, I'd try and find a way to get a deal on any of the other UE speakers. But obviously, everyone's tastes are different.