A pair of Canadian ice climbers have become the first in the world to pick their way up Niagara Falls, parts of which have frozen over winter.

Will Gadd and Sarah Hueniken climbed about 45 metres up on the Horseshoe section of the famous falls, which borders the US and Canada.

Gadd told the ABC's PM program that spray from the part of the waterfall that had not frozen made the historic ice climb slippery.

"Where I started climbing there was probably 20 or 30 feet of ice there. There was about 150 feet give or take of climbing," he said.

"It was difficult because that water makes mist and the mist was actually still blowing onto the ice and I was covering up my ice tools.

"It was a little bit different, it added to the hazards for sure. It was complicated, but yeah, we figured out how to do it reasonably safely and had a great climb."

It has been more than 100 years since American daredevil Annie Taylor got into a barrel and went over Niagara Falls, and several people have followed her path.

Gadd said when he heard someone went over the falls in a barrel he thought it was "crazy", but could not resist the challenge of going the other way.

"The first time I think I heard of Niagara Falls I was a little kid and in Canada ... I heard that somebody had gone over the falls in a barrel and I thought well that just sounds crazy," he said.

"But as an ice climber ... it's just the most amazing waterfall in the world. It freezes just enough that it's possible to climb it.

"I wasn't too worried about getting hit in the head with somebody going over the falls in a barrel, that fortunately doesn't happen much."

Will Gadd celebrates his historic Niagara Falls ice climb. ( Red Bull: Christian Pondella )

Gadd said the climb was not easy, but safety was a priority.

"The climb was serious. It's an upper incline, it's not something that I would recommend to too many people in the world," he said.

"But it's overhanging so the ice tends to fall off behind you and you can be relatively safe with that and I spent a fair amount of time organising the area and working with a really good safety crew with the New York State Park Police to make sure that things were going to be reasonably safe.

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"But ... anything really worthwhile in life has some hazards and this to me was worth those hazards. I felt like I could do it reasonably safely and did in the end, but it's Niagara Falls."

Gadd said while there were other waterfalls he would like to climb, Niagara was "the big one".

"There's only one Mount Everest, there's only one Niagara Falls and I feel really lucky because that ended a lot of hard work by a lot of people and I got to climb something to me that was really amazing and really beautiful and a whole lot of fun," he said.

"So I feel quite lucky and I think I'm just going to focus on that for a bit and try and warm up, I got really cold too."