My in-laws have one of those above-ground pools you buy in a box at Wal-Mart. It’s actually perfect (but I wouldn’t want it in my yard). Cheap, has a filter, easy to maintain, and great for the kids. I think they got the biggest one, about 18 feet across and 4 feet deep. They live down the street from us, so I take the kids swimming a few times a week. They love it. I’ll go in the pool on really hot days, but mainly I sit in the shade with a book while they swim.
And, we live only a few minutes’ drive from the town beach. My kids will go in the water, but I don’t get much more than my feet wet. It’s Long Island Sound, and it is cold! Later in the summer it warms up a bit, but then the jellyfish arrive. I have to desire to know what it’s like to be stung, so I still stay out of the water.
When I was a kid, we lived a block away from the neighborhood pool and swam almost every day in the summer. Then we moved out to the country and had a big pond to swim in. On weekends in high school, I’d go with a friend of mine to her family’s lake cottage (this was in Indiana) and we’d swim there.