"It’s a team effort. I can’t do it by myself," the Dunedin ultra-marathon runner said yesterday.
"It’s a beautiful part of the country."
Five running club friends will take turns running beside him when he leaves Milford Sound on May 6.
He plans to walk the mountain sections and snatch a few 20-minute power naps.
Over the past 10 years, Mr Sutton has tackled many ultra-marathons, including "The World’s Toughest Foot Race", encountering temperatures up to about 55degC during a 217km non-stop run from Death Valley to Mt Whitney in California in 2019.
He has created the Milford Sound to Mt Cook event, and aims to run his longest ultra-marathon, bettering his previous effort of about 420km, from Haast Beach to St Clair Beach.
He will also raise money for the Otago Community Hospice.
Every year the hospice faced a fundraising shortfall of $2.5million and he was keen to both raise funds and awareness of the hospice and its fundraising needs, he said.
After receiving a great deal of help from the community and friends for his many running events, he was keen to give something back.