* It winds through 96km of dense rainforest, boggy swamps and tall grassland, and rises to more than 2,133m (7,000 feet) above sea level at its peak.
* Trekkers must hike for seven to 11 hours daily, and they burn an average 4,500 calories daily for about eight days.
* Riders in the Tour de France burn an average of 6,100 calories a day over 21 days.
* The “Crucible”, an extreme USA military training programme, sees soldiers burn 4,700 to 6,100 calories daily over three days.
(It is recommended to burn about 150 calories a day, the equivalent of a half-hour walk, to be healthy).
* The number of Australian trekkers has jumped from fewer than 100 in 2001 to about 6,000 per year retracing the steps of WWII troops and paying homage to the 600 diggers who died repelling the invading Japanese forces.
* Up to 50 trekkers a year have to be airlifted out by medivac.
* About 80 operators conduct tours along the track with most taking from seven to 12 days to complete the trail.
* Tour operators refer to the first few hours of the trek as the “death zone”.
Australian deaths while walking the track.
2001: One death, particulars unknown.
May, 2008: Shane Green, 32, Perth.
April 17: Samantha Killen, 36, Hamilton, Victoria.
April 22: Chris Frost, 26, Launceston, Tasmania, formerly of Taree, NSW.
Sept 27: Paul Bradfield, 38, Townsville.
Oct 4: Phillip Brunskill, 55, Epping, Sydney.
Aug 11: Nine Australians die in plane crash en route to walk the Kokoda Track.