What do you mean by something original? Every water park is based on original IPs
I'd say a perfect water park would be -
1. Minion Beach
2. Bikini Bottom
3. Delfino Plaza (yes... Nintendo and Universal must happen
)
4. Lake Town (maybe as a link between this and the 4th gate?)
5. a new Lost Continent/Atlantis area? (if they decide to use the IOA one for Wonka, HP Phase 3, or more Seuss)
6. Amity Village
7. completely original area devised by Universal Creative
I'm expecting 50% water slides, 40% water rides (log flume, river rapids, water coaster, POTC-style boat ride, etc), with a few flat rides thrown in as what has been alluded to earlier. They might even reuse the Nuthouse Coaster that's supposed to be removed from KidZone. It'd be a compact dry ride for those who want a break.