Highwire expert Nik Wallenda will walk across the Grand Canyon on a tightrope in June (13) - and the death-defying stunt will be televised live across America.

Wallenda will make the trip without a safety harness, and risk plummeting 1,500 feet (457 meters) to the Colorado River below.

Known as The King of the High Wire, Wallenda became the first man to cross Niagara Falls on the highwire last year (12), but he's still haunted by the death of his great-grandfather, Karl Wallenda, who fell to his death when a televised stunt went wrong in Puerto Rico in 1978.

Announcing the news of his latest stunt on America's Discovery Channel, Wallenda says, "The stakes don't get much higher than this. The only thing that stands between me and the bottom of the canyon is a two-inch thick wire. I'm looking forward to showing the audience a view of the canyon they've never seen before."