I had this great old pine in my backyard, the tree was taller than my two story house. I always wanted to climb it but I could not find a place to start. Then one day we had a big snow storm and at the bottom of the tree there was a small opening. I was able to go into the opening and climb the tree. I couldn't get to the top of the tree instead I made it about three fourths of the way there. It was like my naturally made tree house, I was able to keep some outside toys in the tree. The best thing was my older brothers could not figure out how to climb the tree. So if they were annoying me I would just go in the tree.