There's not too many people who run 100km for fun. California-born Dean Karnazes has been dubbed the “world’s fittest man’’, having run 50 marathons in 50 days in 50 states in the United States; run 550km over three days and smashed all the planet’s most challenging ultramarathons. And he is on the Sunshine Coast for the Blackall100, a 100km run (although runners can choose the 50km circuit) through the Blackall Ranges, starting at Mapleton.