Recently I tried adding all four of the diving lots from Isla Paradiso to Moonlight Falls, but only Rocky Reef was supposedly added properly. The other three were placed above the water. I tried with Rocky Reef again, but discovered that my Sims can't boat there. And the snorkel and scuba dive interactions aren't available. Yet the play in the sand interaction is available. I saved the game and checked Isla Paradiso to find that all the objects in Rocky Reef minus the messages in bottles and buoys were firmly below sea level. Whereas when I placed Rocky Reef in Moonlight Falls, the tall kelp was above sea level. The buoys were in mid air, forcing me to rearrange them. And you could see the objects through the water even when zoomed out.

Apparently the objects weren't placed in deep enough. But I have no idea what I'm supposed to do. I checked the list of worlds that could have diving lots placed in them. And Moonlight Falls was NOT on the list of worlds that weren't compatible with diving lots. So it didn't occur to me that I would have such trouble. But the biggest problem I have now is when I try to bulldoze the diving lot. I can't completely bulldoze the place so everything is back to normal. Because I get this large square bit of land where the lot used to be.

So I had no choice but to exit without saving, go back into my saved game, and manually delete all the objects that I was able to grab and delete them. The lot is still there, but almost all the objects are gone. And I changed the height of the terrain, so that the terrain is well underneath the water. I'm still not sure what I'm supposed to do to bulldoze the lot so that the water appears without the square bit of blue land. Less still am I sure what I'm supposed to do to successfully place diving lots for my Sims to scuba dive and snorkel at.

I did have it set to a diving area. But I haven't got really got the time or patience to make my own diving lot any time soon. Since I'm still fairly new to diving lots.

It could also be the case that even though a world is listed as suitable for diving lots, they only fit if you build them yourself from the scratch. I noticed this in Hidden Springs. It's also said to be suitable but adding the dive lots straight from IP doesn't work. They remain way over the water level, no matter what you do, unlike... say... in Lucky Palms. I've build dive lots before, so that's the route I have to go with Hidden Springs. That or manually lower the seabed in CAW, which of course raises other issues around the world.

Also, even if a world is marked suitable, it doesn't mean that dive lots fit anywhere or that it is suitable for several dive lots. The world could have only a one single suitable place for just a one lot.

Another option is to add a world like Suadiva as a vacation world with NRaas Traveler and go dive there whenever you want. Not the same, of course, but works for me for now.

I think that after you place the dive lot you save your world and then return to main menu to reload world and see if it works properly.

I have tried to place a lot over the blue square, but it won't let me place it in the exact same spot. But I will try and see if any of the recently suggested methods work.

I've managed to fix the problem. It appears that the cause of the problem while bulldozing was because the somehow the lot automatically changed itself from a diving area to "No Visitors Allowed" sometime between placing the lot and me trying to bulldoze it. Well that's great, because I've managed to fix the problem! :D