Balance on a suspended webbing line stretched between two anchor points—it's like tightrope walking that anyone can learn. Slacklining dramatically improves balance, core strength, focus, and proprioception while being surprisingly meditative. Start with lines 2 feet off the ground, use a tree or pole for support, and practice standing before walking.
Most beginners can take their first independent steps within an hour. Setup in parks, backyards, or between trees—slackline kits cost $50-100. The slack community is welcoming; you'll find practitioners in most cities. Progression is addictive; advanced slackliners perform tricks, cross canyons, or walk at extreme heights.