A slackline taken to heights falling from would be fatal. Requires a leash and harness for experienced slackliners and only the greatest go free solo. No beginners.
Rigging a highline involves multiplying, equalizing and stabilizing huge forces on anywhere from the sides of cliffs to the tops of spires. Highlines have been rigged between trees, over rivers and across massive canyons.
At the time of this post, no one has ever died from highlining, because those that rig highlines are extremely experienced.
Andy Lewis, Jerry Miszewski and Damian Cooksey are some of the best highliners in the world.