Approximately 2,400 competitors from 40 countries crossed the start line Friday of the seventh edition of the 165-kilometer Ultra-Trail Mt. Fuji, an annual ultramarathon that traverses the trails encircling Japan's tallest mountain.

The UTMF, with its cut-off time of 46 hours, is the sister race to the Ultra-Trail Mont Blanc and is part of the Ultra-Trail World Tour. It starts at Kodomo-no-kuni in Shizuoka Prefecture and finishes at Kawaguchiko, a town in Yamanashi Prefecture.

About 70 percent of the course is unpaved, and the route follows the trails, paths and forest roads around the foothills of Mt. Fuji, a UNESCO World Heritage site. The runners will experience a total altitude gain of approximately 7,942 meters.

Last year, when another race was held over a similar 92-km course, 72.8 percent of the runners finished the race.

An ultramarathon is any footrace longer than the standard marathon length of 42.195 km raced either over a specific length -- usually 50 or 100 km or 50 or 100 miles -- or for a specific time, with the winner of the latter being the person who covers the most distance.