Where to start...
Basically, the keywords you'll want to look for are "Liminal spaces" and "The Backrooms".
It all started with a picture posted on 4chan in 2018. What it showed was a HobbyTown that was empty in order to be renovated. But with the complete lack of furniture and the neon lighting, the image gave the impression of an eerie abandoned office building.
https://archive.4plebs.org/x/thread/22661164/
In a reply, the place shown in the image was referred to as an otherworldly place called "The Backrooms". And thus, The Backrooms was born.
https://knowyourmeme.com/memes/the-backrooms
The Backrooms alone, with its aesthetics, evolved into a "found footage" creepypasta video from 2022...
https://www.youtube.com/watch?v=H4dGpz6cnHo
...several video games, starting as early as 2020...
https://bloody-disgusting.com/editorials/3614536/play-shad...
...and even a film that's scheduled to come to the theatres this spring.
https://en.wikipedia.org/wiki/Backrooms_(film)
But liminal spaces go beyond that because more and more settings were found to feel like liminal spaces.
https://knowyourmeme.com/memes/cultures/liminal-spaces-ima...
This quickly went from empty office spaces to hospital and school corridors... to abandoned malls... to parking decks... to underground stations (here we get wall and sometimes ground tiles already)... to the same, but flooded (here we get the water)... to public swimming pools. Often only dimly lit, with water in them, maybe with some sparse decoration, but with not a single person in sight.
There's a subreddit about liminal spaces.
https://www.reddit.com/r/LiminalSpace/
In fact, level 37 "Sublimity" of the Backrooms game is a public swimming pool. The fan nickname of this level is "The Poolrooms" because it's The Backrooms, but as a pool.
https://backrooms.fandom.com/wiki/Level_37
This level, this setting alone achieved such a cult status that "Poolrooms" became their very own phenomenon with their own subreddit...
https://www.reddit.com/r/poolrooms/
...and video games like Poolrooms and Pools.
https://store.steampowered.com/app/2978690/Poolrooms/
https://poolsthegame.com/
Interestingly, most poolrooms aren't even real. Some are, but most were made in Blender.
If the OpenSim community was savvier in terms of Internet phenomena, more creative and less hell-bent on making everything look like "Second Life decked out in only the newest and most expensive premium stuff", we would have had tons of such places in OpenSim since the early 2020s. OpenSim is perfect for not only liminal spaces, but Backrooms-like stuff, both in terms of technology and in terms of "you're guaranteed to not encounter anyone else as you're exploring these places".