I had the same question last year...they are all 4 1/2 ft in the middle. Unlike other pools which have a deep end and a shollow end on the opposite side. The POP pools are the same depth around the perimiter, and get deeper towards the center. Sort of a funnel shape.
BTW The lifeguards at these pools are some of the greatest I ever seen. Also, the pools stay open if its raining. As long as there is no lightening within 5 miles (something like that), the pools are open.
The kids got a real kick out of swimming in the pool in the rain.