As I mentioned in a previous post, I love to climb. Balance and body awareness is very important to climbers and circus performers alike. A "Slack Line" is nothing more than a webbed rope, similar to a seat belt, stretched over a short distance a feet above the ground. My children and all of their neighborhood friends refer to it as a tightrope.
The goal of a slack line is to balance yourself on the line. There is actually an international competition held every year for people who do amazing tricks while balanced on 1.5 inches of webbing. Our household is still trying to walk from one end to the other without falling off. To entice my children, we've promised a brand new toy as soon as they can do this while we are watching. After 10 minutes on a slack line, be prepared to feel your abs burn the entire next day. It's a great core exercise.
Typically a slack line is strung between two trees. Unfortunately our trees have yet to reach puberty and would not support the high tension that is required to install it effectively. Instead, I dug a hole 4 feet deep into the ground at either end of the slack line and dropped a chain in the hole. While holding up a portion of the chain, I then poured cement into the hole. After the cement dried, I now had two anchors that I could tie off the slack line. However I still needed to support the slack line above ground. So I two support "trees" from scratch. I built them so I could adjust the height of the line as needed.
Lessons Learned: Don't leave a four foot hole exposed when your son is still outside. He climbed in and couldn't get out by himself. Years of counseling should fix his fear of being trapped by the time he turns 18.