We have found a few different water parks that are free around the Tampa area and the girls just love them. One is the Y in North Tampa I think its the Bob Sierra Y. It is AWESOME there is this big thing right in the middle with two slides one really big and one smaller. The water is only a foot tall at its highest, but the girls still get caught under water and don't realize they could just "STAND UP". On more then one occasion I have had to pluck someone out of the water as they are just doing somersaults under there.
The other park is the Dell Holmes in St Petersburg. It is cool cause its got all these jungle gyms to play on. There is what they call a "splash pad". I call it a baby "car wash" That's what it reminds me of. There is no standing water and just fountains and sprays. The girls seem to like both. I think I prefer the Y cause its a little smaller so I don't loose them as easy.