Here is an NYT article about the surge in water park attendance and construction over the past couple decades, i.e. after our country abandoned the pool as a public place. Here is an old post of mine with data showing a peak in swimming during the late 1980s, and a pronounced decline since, no matter the age group.
This is not one of those changes that you need data in order to be convinced of. I still remember thinking, during the summer of 1993, "Wow, is this turn-out weak or what?" It seemed like there were no more than a dozen or so people at the pool on a summer afternoon. At the time, I chalked it up to moving to a new part of the country, where maybe going to the pool wasn't such a big part of everyday life in the summertime. But, no, it was just the early stage of social fragmentation.
The shift toward water parks has both a quantitative and qualitative side to it. Because water parks are fewer, farther away from home, and more expensive to get into, the percent of the population going to a swimming area is not staying the same while moving from one type of place to another. It's shrinking. The water park is no substitute in sheer numerical terms, as confirmed by the data in that post above.
Aside from that, the kind of activities and who you engage in them with is so different at the water park compared to the pool. No children or teenagers, or probably college-age kids, will go to a water park by themselves. They're brought along by their parents, part of the broader pattern of playing with your parents instead of with your peers. It's not as though the family splits up and meets up later -- it has to be 100% family involvement. "Fun for the whole family" -- how about having fun with kids your own age, while the grown-ups socialize with people their own age too?
When they're going off to a water park, kids cannot hang out with their friends, unless they can badger their parents into bringing a friend along. Still, how many friends are their parents going to spend all that ticket money on? It used to be common to head off to the pool in a group of five or six friends, perhaps meeting up with another group of five or six by coincidence once you got there. You could either walk or ride your bikes (back when children had their own mode of transportation...).
Not to mention all of the other kids your age ("peers") who you weren't already friends with, or didn't know at all. You could make new friends, even if it was only for a day. Autistic people seem to think that it's meaningless to have a one-day "friend" -- like it's either BFF or nothing at all. In reality, people feel a connection to their peer group and community by entering into all ranges of interactions with others. It's reassuring and fulfilling to know that you can just show up to the pool and find a bunch of people to have fun with.
In addition to having fun, you're also maturing socially and emotionally through all the give-and-take interactions with your peers. Unlike your kin, they don't automatically extend you respect, care, and so on. You have to earn that by acting pro-socially in that group setting. And especially for boys, it's a great way to do that while also giving an outlet to their aggression, competitiveness, and rambunctiousness. Who can make the biggest cannonball? Who's not afraid to jump off the high-dive? Who's going to go say "Hi" to that cute, intimidating high school girl over there? Hey guys, grab my foot and launch me up into the air! (OK, but only if you launch me next.)
Not to mention negotiating the subtleties of the splash fight or splash war. Too aggressive, and you're cast out as the brat -- not the bully, since we could splash that aggressively too, but are trying to basically stay on everyone's nice side. Too weak, and you're acting like a sissy and spoiling the fun -- splash back!
And then there were more regularized sports that we invented like gutterball. Anyone else play that? Only one post on the first page of Google results for "pool gutterball" refers to the game. It's obviously written by an adult who played it as a child, and may be trying to pass it on to others. But since he seems to be the only one writing about it, it must have joined all the other games that kids used to play.
Is that something that today's helicopter parents are aware of -- that parents don't transmit much culture to their kids, that they want to pick it up from their peers? You can try to teach your boy how to play gutterball at the pool, or teach jump-rope rhymes to your girl, but if they sense that it's not part of the broader culture of children, they'll junk it. It's not relevant to their social group, so why bother incorporating it into their culture? They're no more likely to prefer speaking German if their peers do not, even if their parents do.
Some of the nerdier helicopter parents think that if they can reproduce the media and pop culture items that they had growing up, their kid will appreciate it in more or less the same way. Guess again -- playing Pac-Man was not primarily about the game itself (unless you were a huge video game nerd), but about the social experience of leaving the house, hanging out in a dark place with flashing lights, surrounded by other kids, with no adult supervision, and using video games more as a means to getting that initial jolt of excitement, to get things started. Mostly, though, the lure of the arcade was that feeling of belonging to a crowd, and everyone feeding each other's high.
Your kid today isn't going to grow attached to Pac-Man because the physical environment of arcades, and the bustling social scene that supported them, are long gone. Only if he develops some OCD behavior centering around vintage video games, or if there's a peer-based revival of those games, will he have much interest in it.
Well, so what if kids these days don't grow attached to Pac-Man, right? But all of that other stuff is more important -- the culture that kids pass on among themselves, and invent themselves. Playground games, urban legends, slang words, nicknames, gestures, and all those other group membership markers. As a parent, you are impotent to pass that on to your kids. (Just try.)
I think even things like nursery rhymes, which you'd think parents would have more control over (they don't circulate among the toddlers themselves), are still a case of broader community input. Like, if you don't hear any of your teachers, daycare workers, babysitters, or school librarians reading them aloud to you, it doesn't make that strong of an impact.
Or if you wanted to involve those non-parental others by reciting some nursery rhymes to them -- what happens if they don't know them, or recognize them but do not feel motivated to keep oral culture alive? That's going to be a let-down, and you'll lose interest in them after that, since it's only something that your mom thinks is cool.