Ryan, 26, was a late entry after arriving in the Alaskan capital less than 48 hours earlier to participate in Geoff Roes' ultramarathon camp.

He won the race - which also features 25 and 50-kilometre events - in a blistering 39 minutes and 18 seconds.

Ryan said he was thrilled with the victory.

"The officials were quite shocked that I had run under 40 minutes on this course as it was of a difficult nature," he said.

"I was swamped with local runners quizzing me about where I was from and what I was doing in Juneau of all places."

Ryan said the race - an 'out and back' route five kilometres up the Perseverence Trail - did not go according to plan.

"I wanted to take the first part of the race easy and try to sit in behind the front runners until the turn-around point, where I would make my move," he said.

"But then I found myself out in front setting the pace with a slight lead on the main group.

"I got to the turn-around point with a minute lead on the chasing group and I pushed from there as planned."

Ryan said the scenery was breathtaking.

"I couldn't take my eyes off the snow-capped mountain we were running towards," he said.

"All three distances of the race were run on the trails around Juneau. There are 63 different individual trails - it's a maze that you could quite easily get lost in."

Ryan spent a week at Roes' Alaska Mountain Ultrarunning Camp.

"I was fortunate enough to receive a part-scholarship to spend a week with Geoff, who is one of the best ultramarathon runners in the world," Ryan said.

"The equivalent of this would be playing one-on-one with LeBron James."

Ryan spent six days training with eight runners from across the United States.

"We spent our days up in the mountains running as they like to say 'mile after mile'." he said.

"The exertion felt effortless because of the simple enjoyment of being high up in the mountains."

Ryan flew from Juneau to Boulder, Colorado.

"It's the 'it' place for endurance athletes," he said.

"While I'm here I will be attempting to reach as many 14,000-feet mountain tops as possible in six days."

Ryan said his ultimate goal was to qualify for the world's oldest, most prestigious 100-mile race, the Western States 100-Mile Endurance Run.

"Living in Australia makes it hard as there is only one qualifying race in Australia and one in New Zealand," he said.

"Not only do you have to qualify, you also need to be drawn from a lottery as the field is capped."

Ryan will holiday in New York and London before heading back to Australia, where he will concentrate on securing a berth in one of the world's ultimate endurance tests.