We had our summer 2012 in Splash Island that is within our town - too close to home.
Splash Island claims to be the first water theme park in the country. The place is huge--7 hectares big and has 6,000 guest capacity. It does have a theme-park feel to it and unlike the usual resorts in Laguna (notably in Pansol, Calamba and Los Banos), where there are only swimming pools, there are lots of other things that you can do inside. There's zip line, wall climbing, basketball hoops and many more.