An underground icehouse? I admit that sounds both awesome and scary. Our biggest exploration happened in the late teenage years, when we found an abandoned mental hospital. It became a travel destination for folks in our age group. Hilarious seeing a group of 20-30 teenage kids freaking out over every little sound when they're exploring.
I agree with
Turret, though - I want to know what was actually carved into the tree. I imagine it being something simple and stupid, like a W+L or whatever, but it would be interesting if it were something more, like actual dates or a message. I would be thrilled beyond imagining if I were able to find some evidence of my happier youthful times like that.