Well, I think you know what my take on it is (see all the Oto-in-the-mountains pictures or my pictures from my brief outing to my grandfather's place in Russia).
My best experiences were actually in the same area as my grandfather's place, the Karelian Isthmus, when I was about 6 (so, just before the fall of the Soviet Union). We went on this series of two-week camping trips up and down the Vuoksa river (which is really just a series of lakes) - se we would travel on rowboats and sleep in tents. We had this deal - my dad is a professional musician, as some now, so as long as he provided entertainment we went for free.
The groups were about 30 people on average I would say, and there'd always be some kids so that was fun for us, but I actually liked talking to the adults too. There would always be like 'official' group games and campfire events, and plenty of time to just go off exploring on your own, either by boat or by foot. I remember having to be careful when going by foot though, since there was a lot of artifacts left from World War II (though the most dangerous I bumped into was rusty barbed wire).
Probably one of my brightest memories from that is one time that we sailed by night instead of day for some reason. Now, that place is far enough north that there is no actual nights in June/July, rather a period of twilight. So I remember this really eerie, quiet twilight with the boats going through the mist - but I couldn't fall asleep because that quiet was constantly broken by MiG-29 fighters flying from the nearby airbase
Strange mix there.
The nature is amazing though. You can again look at some of my pictures from the same area in my Russia thread. I always said it was my most favorite place in the world. I totally want to go to Finland since I believe further west the lakes are even better.
Another sort-of-outdoors experience was my trip to the village where my grandfather was born. It wasn't that I slept outdoors, but I spent most of my time there - "working" as a cowboy. That was also one of the coolest jobs I yet had. I loved driving my little herd of cows, they're cool animals