If you need a speaker for pool parties (emphasis on the party), get yourself a Wonderboom 4 or two. We say two because they're only $100 each, and they allow you to sync two at a time to one device.
After listening to all of my Spotify favorites in areas of all sizes, I can say this versatile device is my favorite mini-speaker for enjoying loud and rich audio everywhere. My Move 2 was provided by ...