Who is the best tree climber in the world?

Tree climbing may elicit childhood memories of scrambling up a craggly walnut tree in the backyard.

But the International Tree Climbing Championships is serious business in Christchurch.

Organised by the 100-year-old International Society of Arboriculture, its prestige event is being held in New Zealand for the first time.

It turns out Kiwis are quite good at tree climbing.

In the event's 50-year history, New Zealanders have won 15 championships with four women taking eight titles between them and two men winning seven titles.

Reigning women's world champion and Mount Maunganui local Steph Dryfhout is hoping to pick up her second title.

As she dove between branches in the work climb event this morning, there was boisterous cheering and clapping for the Kiwi favourite.

"It was actually a bit overwhelming at the start with everyone cheering, but I kind of blocked it out and - yeah - I really appreciate it. It's really awesome," Dryfhout says.

"It's really nice to have the support and I so appreciate everybody making a big effort to come and see it."

Like most competitors, Dryfhout is an arborist by trade.

"When I left school, I did an apprenticeship at a tree nursery and that kind of got me into the passion for trees. But it just wasn't quite enough and I saw a video of someone climbing, and I was like 'that's me'.

"I always loved sports, so it kind of mixed the two."

The tree climbing championships combines all the skills of trades with the competition of a sporting environment.

Events include the work climb - a sort of arborist's obstacle course up the top of a tree; speed climb - the clue is in the name, with the winner the fastest to the top of a tree; and aerial rescue - which involves bringing a 150-pound dummy off a precarious perch, all while talking judges through the strategy and execution.

Barton Allen-Hall knows a thing or two about the sport.

The Melburnian is the reigning and three-time men's champion.

"So much goes into preparing for these things, like a lot of blood, sweat, and tears," he says.

"When you finally get the win after I had a couple of close seconds, and it was a decade of competing before I finally got the World Championship, so it meant a huge amount.

"I shocked when I won the first one - for sure. And shocked when I won the second one. And a bit shocked when I won the third one.

"It took me a long time to get the first one, but then I've won the last three so I've been on a bit of a roll."

While plenty of spectators quietly told RNZ that Allen-Hall is the favourite for a fourth crown, he is not taking anything for granted.

"I mean, there's definitely the belief, but there's also the awareness that it takes a lot. There's so many opportunities to make a mistake, so much has to go your way, and you have to do a lot of things the right way and perform really well to take it out," he says.

There are 91 competitors from 28 countries competing at the International Tree Climbing Championships in Hagley Park from Friday to Sunday.

The masters will be crowned on Sunday when the best of the best take each other on.