first, I'm just amused by decisions made in game behavior. This is NOT a request for game help. I'm not fixing anything in this neighborhood. offers of help, instructions, and redirects to help will be gently ignored.

Sims in one neighborhood have an outdoor pool. They frequently crowd it, and enjoy to their hearts content. Sims in another neighborhood are surrounded by sea water. they maintain an indoor pool, the only one allowed in the neighborhood. Only, when they go inside they stand around talking and NO ONE is swimming. I laugh at the screen and insist they dive or go down the ladder. "Oh come on! Last time I built a hood, those sims swam indoors and I haven't installed anything new. What's wrong, did someone dump vinegar in the pool today?" I rebuilt a few lots. Sure enough, outdoors always swim. Indoors never swim.

And despite all facts to contradict it, I assume your sims do not obey this rule. I laugh and let my sims continue. Suits them, I say.

Vinegar, or something else of a similar color perhaps... Sorry, I couldn't resist!

I was so happy for the full thirty seconds after reading Phoeberg's comment, when I was still wondering what's wrong with white vinegar.
Then I remembered apple cider vinegar.

Your vinegar quote reminds me of the Sims 1 days when it was the slogan of Killersims Shopping Mall simply changing blue to yellow made them so popular. As for vinegar, it made me laugh and care when I saw my cat's reaction to vinegar. (The cat is safe).

Yeah, cats hate the smell of vinegar.

I build nice swimming pools for my Sims and the only one that enjoys it is the random teen that follows my kids home. I am beginning to wonder if everyone in Pleasantview is afraid of a *Skip Broke* if you know what I mean.

I built a community lot with a pool..... don't usually do a comm. pool; even in Strangetown.
Anyway... the only sims that swim in it are the ones I'm playing !!! I thought townies and other sim playables (that I'm not playing at the moment) would swim as well... kind of like a public pool.
But noooo...

I once had a "Sim Brother" house, and the only time anyone swam in the pool was when they were forced to do so to get from one side of the house to the other...

I stopped building them most of the time because they take up a great deal of space and yes, the only time my Sims use it is if I essentially command them, "Get IN there!".

On the other hand, put a hot tub somewhere, and they'll stay in there all night!

Sims can swim in tiny pools. I'm not sure what the smallest size is, but it may be 2x3 or even 2x2 (the size of a hot tub).

I don't know why your sims don't swim; mine do all the time. They love swimming. Well, not all of them. The more active sims love to swim; the more lazy ones love to hot tub. I don't give them pools on residential lots, though. Since I like taking them to community lots, community pools are the thing. My favorite lot at Sim State is the Campus Swim Center I built, in Widespot is the Swimming Hole, and in Drama Acres the swimming pool is a major draw for Drama Acres Park. I don't like the Fiesta Swim Center at LFT or 94 Road to Nowhere, though - they're way too big. The Swimming Hole is a 2x3 lot, and that's plenty big enough for a pool, restrooms, picnic area, and hot tub. Don't make it too big, give them multiple ladders and diving boards relatively close to the entrance, and don't have a lot of other things on the lot - they'll swim.

Oh, and one other thing-there are some sims who are afraid of water-they refuse absolutely to dive into the pool. You have to gently coerce them to get into the pool, and then they'll discover they love it, once they get over the fear of water, and find it fun.
Once that's done, they'll never refuse to get in again-it just takes a couple of fitness points to get them started swimming.