A strong contingent of Blue Mountains runners will take on the internationally-renowned Ultra Trail Australia in the Upper Mountains from May 16-19.
The festival hosts almost 7000 runners from around the world and features five distances - 100, 50 and 22km, the Injinji 1km-4-Kids and a new distance this year, a steep, stair-laden 11km.
Warrimoo runner Andrew Lee will take on the 100km event for the 11th consecutive year, a race he won in 2009 and 2010.
The 49-year-old says it's the atmosphere, the camaraderie and the love of the sport that keeps him coming back year after year.
He says finishing the event is as much about mental fortitude as it is about the training beforehand.
"You can't run that far in training, so that's where the mental stuff comes into it," Lee said.
"You get some rough patches at different stages, but you've got to grind away through them; typically you come good. I would have more regrets if I didn't finish."
Working in logistics in the Defence Department in Sydney, Lee integrates training into the daily commute, hopping off the train coming home at Lapstone or Glenbrook to run to Warrimoo, and running in his lunchbreak.
He says the key to completing 100km is knowing your limitations and staying within them. "It's such a long way when things don't go to plan," he said.
Contenders for the 100km title include Polish athlete Marcin Swierc, Aussie expat Vlad Ixel now living in Hong Kong, Newcastle's Vlad Shatrov who was third in the Six Foot Track Marathon after winning it the previous two years, and Woodford's Brendan Davies, who won the event last year and in 2013.