Daredevil Nik Wallenda traversing an 1800 foot wire that's fine across the crater of Nicaragua's Masaya volcano, the lava beneath reaching up to 2200 degrees Fahrenheit.

There's a very strong draft right there, wearing a gas mask and oxygen tank will end a battle.

Toxic gas and wind, which affected his aerodynamics and visibility.

Who gas proven under May.

That'll mess with you.

Before his attempt, I asked Belinda about what laid ahead.

The reality is I'm risking my life and we're dealing with Mother Nature relative to your previous accomplishments.

Where's your head at going into this?

Training prepared so hard for this and again.

Years and years have gone into this, but there's a little more angst probably going into this one because of all of the unique elements, because we don't know what it's gonna be like out in the middle there.

Mike Trow for Will Lend.

His uncle is the lead engineer and has been preparing six months for this event, guiding a team of Riggers to make sure that the main wire just over one inch thick and the 116 stabilizing wires state secure.

What sort of surprises have been in store?

As you've been installing this?

Well, the environment has has thrown us a pretty big one.

This gas coming up out of the crater has a significant acid content, and this is one of the stabilizers that that was hooked to the rope.

That doesn't look at that.

That's not good.

This is erosion caused by the stress that was in the rope.

I didn't see it coming, but we've got it fixed now.

The last week in the middle of the night, I'll wake up in cold sweats because of this walk.

Every step is dangerous, but I will start to become more and more relaxed as I get through that gas for sure.

What will you do in the moment when the wind does pick up and you're out there in the elements, I will adjust to that wind as best that I can, and that's that's where my training and experience off walking over the Grand Canyon and Niagara Falls in Chicago in New York City.

All of that combined is the only reason why I'm able to take that first step on Wednesday night.

Fighting the elements is nothing new for Belinda, whether it's teetering on the edge of the Grand Canyon, walking blindfolded 600 feet above the Chicago skyline or crossing Niagara Falls.

Well, Linda has been pushing the boundaries of what's possible for decades.

His 26 minutes I'm gonna do this thing New York City world.

Last year, Well, Linda and his sister Liana, made history once again 260 feet above Times Square in New York City, 1300 feet on a cable no thicker than a garden hose.

To do something that's gonna literally leave my fingerprint on the city's pretty exciting.

The will lend a family known famously as the Flying Wallendas trace their roots to European circus performers all the way back to the 17 hundreds.

Testing limits is in their DNA.

Nick and Liana or seventh generation wire walkers.

Their family has been performing mesmerizing feats of athleticism for decades, as showcased in this 1963 documentary for the CBC.

My mom was walking the wire when she was six months pregnant with May have walked, aware since I was 18 months old for me, being on the wire is alive.

There's something extremely peaceful and serene about that, just like some find their peace by going on a dog or reading.

I find my piece by getting on a wire, but in that piece there's a constant danger.

The family has not been immune to the tragedy inherent in the dangers of their work.

Several lenders have died or been injured in high wire falls in 1978.

Nicks Great grandfather Coral Will Linda, a renowned high wire performer himself, fell to his death during a stunt in Puerto Rico at 73 years old.

This video, captured by a local news crew at the time, showing his harrowing final moments and in 2017 a near catastrophe for the family when a pyramid made up of eight performers collapsed at a training session.

It was February 8th, about 10 30 in the morning, we were preparing to break a world record for an eight person pyramid, and as we made our way out on that wire, we lost our balance and the pyramid collapsed.

By the grace of God, I caught the wire.

My cousin caught the wire.

Another gentleman stayed on the wire, but five of my family members and friends hit the ground.

I broke a rib, punctured my right ear.

Canal broke clear through my left humerus.

But the big one was every boat in my face, the trauma doctor said.

When we first got the call, he said, the fear and the voices of the paramedics, he says, I was certainly we're gonna have fatalities by the time they got to the hospital.

But 10 days later, Leon is going home, so it's just hard to relive it over and over again.

It's weird when something that dramatic happens to you every single step of the way.

I mean, that's why I'm a little emotional, cause I'm there again tonight that emotion and history no doubt in the air as well.

Linda achieved his latest dream.

Sage just caught a piece of history right there.

Think I'm keeping this merry go running across nickel Linda off the wire into the history books in Nicaragua.

Thank you for Nightline.

I'm well Reeve at the Masaya Volcano, Nicaragua.

You can watch the entire special tomorrow evening on the National Geographic Channel.

Hi, everyone.

George Stephanopoulos here.

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