Yes, mermaids exist. They can be found in Wet & Wild agogo, until recently called "blue lagoon".
No ping pong balls to throw here, you could try to throw a fish into the water to see a mermaid come and pick it up, but cash money works better if you really want to see one...;-)
Not to be confused with Blue Lagoon II, or the "real" watersports center, called blue lagoon as well.
A good and up-to-date agogo list can be found here.
