That it will be a Wallenda attempting the history-making walk only adds to the allure.

The Wallendas, the first family of the high wire, trace their fearless roots to 1780 Austria-Hungary, when ancestors traveled as a band of acrobats, aerialists, jugglers, animal trainers and a bit later, trapeze artists. The family has been touched by tragedy: Notably, Nik’s great-grandfather and the family patriarch, Karl Wallenda, fell to his death during a walk in 1978 in Puerto Rico.

“I am carrying on the legacy and that does put a lot of weight on my shoulders,” Wallenda acknowledged, “but in no way have my parents or grandparents ever said, ‘Well, you need to do something bigger or better.’

“It’s kind of built into me,” he said, often quoting Karl Wallenda’s mantra: “Never give up.”

Another son of a daredevil legend understands that drive. “Kaptain” Robbie Knievel, the now 50-year-old son of the late Evel Knievel, has been making dangerous motorcycle jumps since he was 8, and isn’t done yet. He made up his mind as a child that he’d continue his father’s legacy and remains committed today.

“It’s something I want to do, carry on the name, the tradition,” he said by phone from his Las Vegas home, “to keep the name Knievel the most famous on two wheels. It’s just something I grew up with and knew I wanted to do.”

It was his own father’s friendship with Karl Wallenda that steered Evel Knievel into performing.

“I’m a dying breed,” the son said. “And Wallenda’s a dying breed.”

Wallenda will have one safeguard, a tether that will keep him out of the water if he falls, but not on the wire. ABC, which is televising the walk, insisted on it. Wallenda said he only agreed because he’s not willing to lose this chance and needs ABC’s sponsorship to help offset some of the $1.3 million cost of the spectacle.

“This is what we do. I feel like that’s taking away from it,” Wallenda said. “I feel like I’m cheating at that point.”

The tether is another obstacle to contend with in a family whose shunning of safety devices is part of the appeal of the act.

“Life,” he said, again quoting his great-grandfather, “is on the wire. Everything else is just waiting.”