The expedition to climb Manaslu (8000m), the eighth-highest mountain in the world, comes 20 years after Mr Cotter (49) first summitted Mt Everest in 1992. It will also be the first time he has guided in Nepal since 2007, when he climbed Everest for the fourth time, and his most significant mountain ascent since recovering from two major knee surgeries.
"I think of every trip as a milestone, but this one is for sure," he said.
Mr Cotter is the owner of Wanaka business Adventure Consultants, a high-altitude expedition guiding company that leads up to 50 international trips a year, including polar skiing and climbing in the Antarctic.
Mr Cotter, who scaled Mt Cook as a 17-year-old, has been forced to reduce the intensity of his outdoor adventures in recent years after developing patellofemoral syndrome, where the kneecaps wear the cartilage off the femur.
"Too much carrying heavy packs downhill, I think, and muscular imbalances."
However, surgeries in 2009 and 2010 had made "enough of a difference" that he was now able to get back to being active in the outdoors after a "slow road to recovery".
The team for the Manaslu trip comprises five experienced international climbers, seven Sherpas and two base camp staff, with Mr Cotter at the helm in his first assault on the peak.
"For the people coming with me, knowing I'm not just repeating something I've done before ... it's an adventure for all of us, and we're going to be experiencing it all together for the first time."
The trip will begin with a preparation period in Kathmandu, followed by a summit attempt planned for early May.
Mr Cotter last visited Nepal in 2008, when he took his father, Ed Cotter, then 80, to base camp to "share an experience with him and be back in the hills together. It was many years since we'd done that."
Ed Cotter, who lives in Christchurch, is also a prominent mountaineer and had not been to Nepal since 1951, when he was a team-mate of Sir Edmund Hillary on an expedition that resulted in Hillary's selection for Everest.
In 1992, Mr Cotter was "about the 412th person" to climb Everest, but since then 3000 to 4000 people had completed the climb.
He would not rule out another attempt on the world's highest mountain.
"I'm not ruling it out, but it's about having a variety of experiences and adventures rather than just returning to the same mountain all the time."
