The team was the first to riverboard one of the biggest white-water rivers in the world and Cournane was thrilled they had accomplished something no-one else had.
"Yes indeed we did it; [it] was a very very awesome trip," Cournane wrote on her sister Alice's Facebook page from Nepal shortly after the team completed the journey on November 29.
The 29-year-old first tried riverboarding when she was 16, in the Kawarau River and since then she had become hooked.
So when she heard about the Sun Kosi challenge, a river renowned for swallowing rafts much bigger than her board, she couldn't resist.
Riverboards are equipped with a set of fins and a buoyancy aid and boarders wear a much-needed helmet.
Cournane said that the journey was worthwhile and harder on the body than she had anticipated.
"We did a lot of kicking ... There was more flat water and slow sections than we expected."
The team met in Queenstown through the New Zealand White-water Boarding Association.
The team included boarders from the United Kingdom, the United States and Israel.
They aimed to finish the expedition within 12 days and on the Nepal Riverboarding Facebook page it was clear they were more than happy with the result.
"Did someone body say world's first? BOOOOM, smashed it. What a team, what an epic adventure, there was illness, injuries, surfing, laughter and more crazy shenanigans than you could shake a stick at.
"It take a special team to accomplish what we managed on the Sun Kosi and Tamur Rivers ... We have pulled off a daring world's first."
