UPDATE: Alexandra Headland runner James McAlloon fell short of his "sea to summit" journey.
He abandoned the trek 25km from the top of Mt Kosciuszko.
"The road to the summit was closed and I was in too much pain to do the 50km return without a vehicle support," he said.
EARLIER: AFTER running from Kings Beach to the summit of Mount Beerwah during January, James McAlloon had an idea.
The 26-year-old wanted to explore his ultra-marathon boundaries. Continuing his "sea to summit" theme, James figured he would just "cut to the chase" and go big.
The task starting tomorrow is a 217km journey from the New South Wales coastal town of Tathra to the summit of Australia's greatest peak, Mt Kosciuszko.
He'll aim to get the job done within three days, running along rural roads before making the final 6.5km mountain journey which alone has a vertical ascent of 2228m.
"I figured if I trained hard and got good enough I could go all the way there," he said.
Growing up in Gympie, post school James spent time in South and North America.
Over the years he has run official and unofficial marathons, as well as been support crew for friends undertaking ultra events. Featuring on his run resume is Detroit and Chicago marathons, as well as longer runs in Patagonia and Santiago in Argentina.
Yet this weekend's epic will be his greatest challenge. An experienced climber, James believes his time in America has conditioned him for the cold weather.
Moving to Alexandra Headland 18 months ago, the current forecast is for temperatures between minus two and six degrees Celsius.
"I know living on the Coast anything below 20 is freezing...I think we are pretty blessed with the weather," he said.
"The temperature looks alright, hopefully there's not too much snow on the trail up Mt Kosciuszko."
Supporting James over the journey will be his partner Emma and friend Ben Sharpley. They'll be in a van decked out with beds and a kitchenette to follow the journey.
James hopes to complete at least 80km on the first day, and wants to run through the 167km point of Jindabyne by day two.
Working in marketing and business development, James has been training hard during recent months. He has been running at least three days a week, with two shorter runs of about 12km and one long, as well as a hike to help build strength. He peaked at 70km for his biggest run, encompassing areas like the Coastal Path, along the David Low Way to Sunshine as well as the Noosa National Park.
"I have always pushed myself with sport," he said.
"The real reason (for the run) isn't for charity and I didn't want to use a charity for my own publicity."