I have visited both of these Aqua Parks with the family with children ranging from 4 to 15. From the reaction of the family (not me personally as I am not really fussed about water parks) the favourite was the Grand Ucel. The Aqua Park in Calis is better if the kids are smaller but the Grand Ucel is better if they are older - and some of the adults proved just how much they are 'still kids at heart' as they loved it aswell. The slides are a lot bigger at Ucel.