How to make a nice rounded pool with smooth transition walls?

Can someone tell me how I could make a nice smooth rounded pool that also has a border around it? I figured it might be best to use a model but was wondering if there is a way to do it with the subdivide tool maybe..

Use subdivide. Make a sqaure-ish pool, and then subdivide the walls, with the floors, and even the deck if you want to make the deck curve into teh water.

Awesome, thanks. I will try that