Continuing with the theme of childhood summers...
I think about a lot of the things I got to do in the summer as a kid. A lot of this depended upon the fact that I grew up in a small, fairly-safe town where you could walk all up and down the street where I lived without too much real danger. (I think the greatest danger my friends and I ran into was a time we stumbled into a hornet's nest).
There was a group of kids (a family with four kids) across the street from me, and there was my friend Elizabeth down the street. With the Kings (the family of four kids), we played a lot of active games, stuff like hot potato, or H-O-R-S-E (the basketball game), or kick the can, things like that. We also used to go "exploring." There was a whole area behind their house that was undeveloped...we just had to climb over their chain-link fence to get there. In my childhood memory it was like a jungle, but it probably really wasn't that grown up. The weirdest and coolest thing was that there was an area maybe a quarter mile away that had all been plotted out and set up for a subdivision...that was then never built. So there were these silent, empty streets, and the places where streetlights would go but had never been installed, and lots set out but no houses. It was interesting and also kind of creepy...we used to talk about how it was like what the world would be like after the world ended and all the people were gone.
That subdivision has since been built. Like a lot of things significant in my childhood, it has changed greatly. None of the kids growing up in what was my old neighborhood will go there to "explore." (Also, I suppose liability is such now that trespassing laws are a lot stricter. Back in those days, if a cop saw us roaming around, he'd just tell us to be careful and be sure to get home in time for supper. Of course, it may also be some of the local cops knew our families, and knew we weren't troublemakers...)
I also used to climb trees a lot. I don't remember if many of my friends were into it. I suppose now some parents would see it as horribly unsafe but I guess my parents knew I was careful. I never really fell - I might have slipped down a branch or two and then caught myself, but I never got hurt. There were several large old quaking aspen trees that I used to like to climb - they were all within sight of the house so I guess my mother felt like she could keep an eye on me. I'd climb up as high as I felt comfortable - I think it was probably about 20 feet or a bit less, because I was at eye-level with the second-story windows of our house - and just hook my arms and legs over branches and look around. It gave a different perspective on the little area of the neighborhood. I tried carrying a book up there but it was never very comfortable for reading.
Interestingly enough, my brother and I never really tried building treehouses. Part of it was, where we lived, stuff like construction waste and scrap lumber was pretty hard to come by.
One of the sadder things of my early adulthood was seeing the main aspen tree I used to climb cut down, shortly before we moved away from there. The vacant lot where the aspen was located was getting developed...
There were other places outdoors to hang out. Between our yard and the neighbor's, there was a dense thicket of honeysuckle and I found in the midsummer, after the flowers were done and the bees had left (I was terrified of bees as a child), I could crawl in underneath the branches and be effectively hidden. I used to go there to read, or I sometimes took small toy animals there with me and acted out stories with them.
We also had a silver maple that by some accident of growth had a big "platform" about six feet up where several branches came out of it. This actually kind of took the place of a treehouse, because it was big enough that you could climb up there and sit.
Also, a few times, I risked my mother's anger and climbed out one of the windows of my bedroom onto the garage roof. The roof had a fairly steep slope and I suppose I could have fallen...but again, it was kind of cool to be up there.
Most places I went to hide or to hang out, I took one of three things: a book I was currently reading, a notebook I was writing a story in, or some of my small animal toys. I used to act out "stories" (for lack of a better description) with them....make up a story and dialog as I went along and move them through it. Sometimes I wrote the stories down but most of the time I just let them grow and evolve and live in my brain...writing was a lot of work, sometimes, and my penmanship wasn't good.
I'm almost embarrassed to admit how late into adolescence I kept up that "game." But I also think that my playing it allowed me to spend time alone, or time where I didn't have much else to do, and use my brain to entertain myself...sometimes even today, as an adult, I will make up some kind of a story in my head to pass the time when I'm stuck somewhere with nothing to do.