This is another big hobby for a lot of people. Flying a model rocket can be done for under $20 (but obviously, some people get much more elaborate). If you are lucky enough to find an event, you can see hundreds of these of varying complexity. But if not, it’s still fun to pick up a starter kit at a hobby shop and build one together then fly it a few times.
There’s a lot more in hot air ballooning than you would think (they’re harder to fly than an airplane) so it’s hard to get someone to take you up. But if you’re lucky, this can be a really fun adventure. If not, they have hot air balloon events where you can watch dozens of them take off at once.
Lots of people get in to riding ATVs and Motorcycles and camping for days on end at the Sand Dunes. It doesn’t hurt AS bad if you wreck on sand, so there are some pretty crazy people you can watch (or be)
There are lots of cool things to be seen if you’re a tourist outside of your state/country. In Arizona we like to go to Mexico because it’s not too far away and it’s quite a cultural experience.
Rope swings can be great fun. Lots of lakes and rivers have already built rope swings (make sure they’re safe!) but you can build your own pretty easily. It’s especially fun if it’s in to water (you could do it when you go cliff diving)
Now that you’re older, you can probably engineer a really cool treehouse or fort. Wood isn’t TOO expensive, and if you already have the tools, you can make a pretty sweet club house either in your back yard or even out in the woods somewhere.
Ask around and you can probably find a nearby lake or river that’s well known for cliff jumping. Usually better in a group and definitely a daytime activity. Combine this with a picnic or barbeque and you have yourself a party!
Most people don’t think of this as a date, but it’s great for a group. If you know someone with a boat, you can go water skiing, tubing, wakeboarding, knee boarding, etc. etc. at a nearby lake.
There are rivers of varying speed and rapid-ness just about everywhere. Grab a tube or raft, some drinks and maybe some music and hit the river! Make SURE to bring sun screen.
Every state seems to have a small town that is well known for tourism. In Arizona, it’s Sedona where you can see red rocks and check out all kinds of neat little shops and trails. There are others in other places – go look for them!