The HURT 100 takes place in the rainforest that rises above Honolulu on the island of Oahu. The terrain is unlike anything in mountain ultrarunning: narrow trail, roots everywhere, near-permanent mud and constant humidity beneath dense tree cover. The difficulty comes from the ground underfoot and the air, not from altitude.
There is a single race of 161 km, split into five 20-mile loops around a central base. That structure makes crewing straightforward and lets runners break the distance down mentally, but it also puts a tempting exit in front of them five separate times. The drop-out rate is famously high.
