Mermaids Park - Diving lot suited for pasting

Branching out from Isla Paradiso, the mermaids and scuba enthusiasts have made themselves a cozy little place to spread the joys of diving to many other worlds out there, small enough to even fit in some rivers and saltwater ponds. Rocks, kelp, a diving cave, corals, bottles, a storage chest, underwater fishes, and decorations both big and small, including some that once used to be ocean pollution thrown carelessly into the sea.

Realising when searching "dive" or "diving" on ModTheSims that there seemed to be no diving lots uploaded in the prior 10 years, I took on the challenge to make the first one suited for public download and use. And it took longer to optimise than I thought at first: 2 weeks of placing and testing the lot in various worlds.

Note that underwater sight distance tends to be poor, a mere 25 squares in most worlds (50 squares in Isla Paradiso). Additionally, the likely need for users to re-adjust surface-level items such as the buoy, meant I had to drop plans to add waterlilies and sea fish to try to fish from boats to the lot.

The dive difficulty is set to 1, the cave to 2, and the chest to 4.

There are two lot versions, both with separate .package and .Sims3Pack zip files. It is recommended to use the standard "All-flat" version, but an alternate "Crater" version is also provided in cases where the standard version doesn't seem possible to get working.

The diving spot is certified shark-free, as I saw no benefit in adding a spawner to add them there.

Worlds where I've confirmed that the lot can be dived down into in
• Confirmed:
• • Sunset Valley
• • Al Simhara
• • Shang Simla
• • Bridgeport
• • Appaloosa Plains
• • Starlight Shores
• • Moonlight Falls
• • Sims University
• • Isla Paradiso
• • Barnacle Bay
• • Dragon Valley
• • Lucky Palms
• • Monte Vista
• • Midnight Hollow
• • Hidden Springs
• • Aurora Skies
• • Roaring Heights
• Confirmed, but shallow water or unusual routing may require extra effort to get the lot to work:
• • Twinbrook (Swamp only, 5m deep)
• • Champs les Sims (4m deep)
• • Riverview (A small portion of the river mouth near Farmer Valley Road has deep enough water, and even then only 5m)
• • Sunlit Tides (5m deep)
• • Lunar Lakes (Requires a nearby subway station, LLAMA box, or teleportation)
• Debunked:
• • Oasis Landing (Although the saltwater line is circa 3m under the Wasteland and can be dug into with terrain shaping, various technical limitations about diving lots and lot placement prevent diving lots from being possible there)

Must-follow guide to place the lot and use it, and tips to try out if it doesn't work
1) Use the cheat code "testingCheatsEnabled true", then "enableLotLocking on", then "buyDebug on".
2) Add a new 20x20 (or larger) empty lot in saltwater.
3) Set the lot type to "Diving area".
4) Place Mermaids Park on that lot. The lot generally can't be rotated or anchored at all during placing, as it'd make the seabed rise to the surface.
5) At this point, the water will be transparent, the seabed will be textureless, and the game has reset the lot type to "No visitors allowed". To counter this, set the lot type once again to "Diving area", and then save the game and return to the main menu.
6) Load the world again. By this point the diving lot should look a lot more normal. If not, repeat steps 5 and 6 until it does. This often takes 2 or more tries.
7) If the buoy is not already ~45% submerged, but the water is deep, enter the lot in Build Mode, add a small terrain height change in the area between the mermaid sign and the tent, then move the buoy as it can now be placed at surface-level.
8) Ensure the Sim has diving skill-level 1 by snorkeling or a course at the science lab, or is a Mermaid Sim.
• If the Sim is unable to initiate diving on the lot (Either by changing from "Dive" to "Swim around" for at least 40 in-game minutes, or by getting reset to the shore), there could be problems with the buoy. Open the lot in Build Mode, delete the existing buoy, and add a new one from the buyDebug item menu over the small crater. Make sure the buoy is circa 40% submerged, and does not hover, be 100% above water, nor be invisible. If no squares on the surface allow 35~45% submerging, try the step below:
• If the Sim gets stuck in the lot bottom in a state of non-diving swimming (which I've had happen to me in Twinbrook), this could mean that the game thinks the water in the landing area is too shallow. Edit the lot and make a further ≥5m deep terrain crater in the area between the mermaid sign, the tent, and the red coral; or try out the "Crater version" download.
• To make mermaid NPCs show up on the lot in most worlds, this requires converting a non-occult Sim NPC. With NRaas Master Controller, this is done by clicking on a non-occult Sim, and going Nraas Master Controller → Intermediate → "Occult: Add" → Mermaid; then Intermediate → Lifetime Happiness → At least 5000; then Basic → Purchase Rewards → Permanent Mermaid.
• If Error 16 (not Error 12) during saving occurs much more often after placing this lot, the cause of it is not entirely clear, but it seems to help most of the time to delete the lot and the area it was placed in, try to save again, and then (if the saving succeeds) restarting the guide from step 1 when placing the lot again.
• Occasionally, there may be routing failures if a Sim drives directly to the buoy in a taxi-boat. For better routing, take the taxi-boat to about 15m away from the buoy, then swim the last stretch to it.
• Seemingly at random after first placing the lot, the cave has a small chance of causing the Sim to be reset to the nearest shore when entering it. If this happens, enter the lot in Buy Mode, Shift-Ctrl-click on the cave, and give the cave a name.

Lot info
Lot size: 20x20
Furnitured: 2,271 §
Not furnitured: 1,007 §

Notes
• The lot should by all accounts work perfectly in Patch 42 through 69 (Tested with Patch 67). For Patch 70, an EA forum user in December 2022 reported having found a workaround for scuba diving in regards to the patch's complete and total breakage of ocean activities. The forum user suggests setting the diving difficulty to 0, but the Diving skill class at the Science Lab is sufficient to get to skill level 1.

Changelog
• 31 March 2023: Version 1.1, which adds all remaining spawners for catchable underwater fish (due to so, so many opportunities requiring them), fixes a rock formation, and uses .package/.sims3pack simultaneous lot uploads.