This is the closest option for you West enders. It's five bucks but it should be enough to cool off your kids and keep them busy for most of the afternoon. It is outside of the county, but it is quicker to get to Oldsmar than it is to get to most of Tampa from here. Tampa and Pinellas have quite a few spray areas, public pools and water fun for kids. This picture is from Cotanchobee Park.