Over 2,000 athletes are expected to take part in the Esat Digifone Warriors' Run in Strandhill, Co Sligo, next Sunday.
The 10-mile race is from the beach at Strandhill up the hill of Knocknarea to the cairn at the top reputed to be the grave of Queen Maeve.
The terrain includes bog, forest and cliffs.
It began in 1979 as a bet between a German tourist and a group of locals as they watched an athlete race up the hill against the clock. He completed the run in 20 minutes.
The Warriors' Run is longer, as it begins on the beach, and the aim is to complete it within an hour. Queen Maeve's cairn is 1,050 feet above sea level, so the incline is steep.
For those not competing, there will be a number of events on the beach, including music and the appearance of a giant Queen Maeve who will race with any children willing to take her on.