Summer was almost over, and this was the perfect chance for everyone in the neighborhood to go to "Neptune's Kingdom", which was known to be the most popular water park in town according to some of the customers who go there. Luckily, you didn't hear anyone else complain while you saw the commercials.
While the water park was famous for giving all the customers a fun time, it was unknown to them that the water park itself leads to a gateway to the underwater city of Atlantis, that was home to the Greek god of the ocean, Poseidon. Most of the people who go there, might never come back as humans, and they didn't mind. Eventually, with all the water piling up at the park, there was a 99% chance that the city itself could sink to the same level as Atlantis did years ago.