There are 3 pools at the beach side part of the hotel at HSB - there is a pool with a slide - nice for kids, and lots of families were at this one. The main pool there gets pretty deep, so not really suitable for small children, and there is another small pool. On the new side the pool area is huge (3 pools connected together) - one part has a sandy beach to it, which slopes into the pool and there are two waterslides which are fun (I have been down them!) The pool is all one depth here - 1 metre throughout.
There is a kids club, but we didn't need it - looked nice though.