Honestly those of you that are arguing about Mantas splash and Diamondbacks splashdown need to sit down, and chill.
So who cares that Manta does not have a legit splashdown, it still looks stunning, as does Diamondbacks. Now those of you that think Diamondbacks splashdown is utterly pointless, the fact of the matter is, your right! It is pointless, but so is Mantas. Nether of these rides needed to have any interaction with water, but they do and because of that each ride is unique in its own way. Every time I am in line at Diamondback I always hear oo's and ah's as the train skims over the water. It is pleasant to look at and gets the people in line excited. Manta does the same, from what I have seen in videos it looks quite elegant so I can only imagine what it looks like in person.
And for those that say you DO get wet on Diamondback, if by that you mean a very light haze of mist and maybe a grazing on the side of your shirt that drys off in five minutes, then yes, you do get wet. Other that that, the splashdown adds nothing to Diamondback, or Sheikra, Griffon, or Manta for that matter. But ask yourself, doesn't the look much more appealing with these effects? As for landscaping, of course Sea World is going to make the area look as great as it can, remember they are competing with mouse!
Basically what I'm trying to say, trying to compare and argue Kings Island and ANY park in Florida is IMHO, outrageous and a waste of time.