“The idea of climbing waterfalls to most people must be completely crazy, and you know, a year ago I would’ve thought the same.”

I’m sat down with James Pearson, a North Face climber of twelve years now. We’re at the brand’s Regent Street Store in London for the launch of Sawanobori, a film capturing his epic quest to climb Shomyo, Japan’s highest waterfall.

Sawa is Japanese for stream, nobori means climb. Sawanbori means stream climbing. Thanks Google. It’s apparently a common pursuit in Japan.

“It’s a tradition that’s happened for hundreds of years,” James tells me. “It’s its own little sub-sport of climbing, in the same way that bouldering or trad climbing is in the UK and US. It even has its own space in any of the outdoor shops in Japan with special shoes and wetsuits.”

It wasn’t always a pursuit or activity though. It began as a means to an end – it had a practical purpose you could say, as James explains.

“Japan is covered in a lot of very dense vegetation, and so going way back in time, the easiest way to move between little villages and settlements was often to go via the rivers instead of trying to battle through the jungle when roads or trails didn’t exist. Fast forward so many hundreds of years and it became an activity, and instead of walking along the edges of streams people started to look to scramble the rocky sections. Then modern climbing gear comes along and suddenly there’s this new sport. It developed at a very similar time as modern climbing did in Japan – to some degree it was Japan’s version of mountaineering. The adventurous climbers out there who’ll often be mountaineering in the winter will be doing Sawanobori in the summer.”

So how did he come across this somewhat obscure Japanese sport? “I came upon it when my Japanese friend, Toru Nakajma, who’s one of the best all-round climbers that I know of, told me he’d been climbing waterfalls in the summer,” James tells me. “I thought, wow if he’s done it, this has got to be something cool. I put together a really quick and short proposal to The North Face as a throwaway idea and they loved it. So with probably some of my least preparation ever I ended up having one of my most incredible experiences.”

Toru and his compatriot Yuji Hirayama joined the expedition, along with James’s wife Caroline Ciavaldini who’s also an athlete with The North Face. James reveals to me that she was in fact pregnant during the trip.