The Barkley Marathons

Tennessee, USA

• Date: TBC (usually in April) • Entry cost: $1.60 • No known website

When the assassin of Martin Luther King Jr. escaped from a remote prison, deep in the woods of Frozen Head State Park in 1975, he managed to run just eight miles before being captured. Unimpressed by his athleticism, Gary Cantrell created the Barkley Marathons race to see just how far you could go in the 60 hours he was on the loose.

The resulting course involves five laps of precipitously steep scrambling and off-trail bramble-bashing. Competitors are required to collect the page numbers of books that correspond to their bib number at remote, unmanned checkpoints on each circuit. In the race’s 36-year history, just 18 runners have completed it. Any year that a competitor completes the course, the route is made harder. Barkley is the last word in the understated and stoic world of ultra-distance mountain running.

The entry process is cryptic. Any competitor who cracks it, and is subsequently accepted, must pay $1.60, and present a number plate from their home state or country as part of the entry fee.