About This Race
The Blood Rock 100 stands as one of Alabama's most challenging ultramarathons, held annually in the rugged terrain of Oak Mountain State Park. This December race tests runners across technical singletrack trails that weave through the park's 9,940 acres of hardwood forests and rocky ridgelines. With over 17,000 feet of elevation gain packed into just over 100 miles, the course delivers relentless climbing and technical descents that demand both physical endurance and mental fortitude. What sets Blood Rock apart is its December timing, when Alabama's typically mild climate can surprise runners with anything from crisp autumn conditions to unexpected winter weather. The race's multi-day format allows the 100-mile field to start Friday morning with a generous 44-hour cutoff, while shorter distance options begin Saturday. The predominantly singletrack course keeps runners immersed in Alabama's natural beauty, with only brief sections on gravel roads and minimal pavement. This is a race that rewards patient pacing and technical trail skills over pure speed.
The Blood Rock 100 course utilizes 92.84 miles of singletrack trails within Oak Mountain State Park, complemented by 7.74 miles of vehicle-free gravel roads and just over a mile of pavement. Runners face 17,196 feet of elevation gain across the park's challenging terrain, which features rocky climbs, technical descents, and dense hardwood forest. The course design emphasizes Alabama's natural trail systems, keeping runners on narrow, technical paths for the vast majority of the distance.
Starting and finishing at the Cabins on Tranquility Lake, the route winds through the park's extensive trail network. The technical nature of the singletrack, combined with the substantial elevation profile, creates a course that demands careful navigation and steady climbing ability throughout the 44-hour time limit.
Elevation Profile
The course gains 17,195 ft over 102 miles, with the steepest section between mile 7–mile 7.
Course Map
Route shown is approximate and for illustration purposes.
Practical Info
December in Alabama typically brings mild temperatures ranging from 30s-60s Fahrenheit, though conditions can vary significantly and may include rain or occasional frost.
BHM - Birmingham-Shuttlesworth International Airport
Oak Mountain State Park offers cabin rentals and camping facilities. Birmingham area provides additional hotel options within 30 minutes of the race start.
Best For
Notable Features
Blood Rock 100 offers runners the rare opportunity to tackle a legitimate 100-mile challenge in Alabama's most diverse state park. The race's December timing provides a unique seasonal perspective on the Southeast's trail running scene, when most regional ultras have concluded for the year. The course's heavy emphasis on singletrack trail running, with over 90% of the distance on narrow technical paths, creates an immersive wilderness experience despite the race's proximity to Birmingham.
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