There's always lots of discussion about the various outdoor rock speakers. I have a pair from Outdoor Speaker Depot and they sound good enough, but I thought I'd throw this out for those folks who are thinking of buying a set. They are great for around a patio, as the speakers in them are angled slightly up from horizontal. But I've found that for hearing the music while in my (inground) pool, I have to turn them up quite a bit, enough that they're too loud for the patio and the neighbors. So, although I haven't tried it yet, I think the better option for pool tunes would be to mount a set of regular outdoor speakers on short posts and point them down towards the pool. This is assuming that your setup is like mine in that the pool is not next to the house. (In which case you could mount them under the eaves and angle them down toward the pool.)
I just thought I'd throw that out for the benefit of those who are looking to buy some outdoor speakers.