And when I say 'fully' I mean 'fully with smoothanim transitions' - just like the waterworks beach towel you won't 'snap' between any of the poses - you Av will move realistically from one to the other... pictures don't do it justice so pop to waterworks and see it for yourself.
Have your own pool, or water from one of those 'others'? Not a problem - it comes with 'PrimSwim Lite' - just drop the copy/trans script into your and you're good to go.. give it away or even use it in your own pool creations.
Like the InnerTube you don't just 'sit' on the water or do some lame 'spinny' - you actually float and can paddle around...
Click on it before you lie down to change between the 12 built in textures, and when you wanna relax, click on it to change poses.
Good times for just $L 350
It's at WaterWorks