Think tightrope walking is tough? Then you haven't seen slacklining, the latest extreme sport in which athletes walk across two points, balancing on a nylon webbing, that has been anchored to both sides.

The biggest difference between tightrope walking and slacklining is that while the line in the latter is under some tension, it is not as rigid, but is instead almost bouncy like a trampoline. Also, use of nylon webbing helps to keep the slacker's foot from rolling. This allows slackliners to be dynamic and perform impressive stunts and tricks, all while balancing on the thin line with no safety net below!

The credit for creating this daredevil sport can be attributed to two California rock climbers - Adam Grosowsky and Jeff Ellington, who first started walking on the loose chains and cables that lie alongside parking lots. They enjoyed it so much that they started tying nylon webbing to higher points in California's Yosemite Valley and walking across it. Soon other climbers caught on. Not only was it fun, but also, a great training tool for rock climbing.

Over the years, slacklining has evolved into a real sport - One with many different variations, ranging from Freestyle slacklining to Waterlining, which as the name indicates is walking across water. However the most nerve-racking is Tricklining, where athletes perform tricks as they walk across.

And, while most of them do it with the nylon web pretty close to the ground, San Francisco resident Andy Lewis takes it to a new level, by performing tricks while slacklining a 45ft. crossing over a 100ft. deep ravine in Flat Sands, California.

But, as the 24-year old full-time slackliner will warn you, while he makes the sport look easy, it is only because he has been practicing since graduating from high school in 2004. In other words, do not try this at home!

Resources:wikipedia.org, slackline.com, dailymail.co.uk