Black River Run is a family-friendly ultra race in Västerås, Sweden, held over a September weekend and organized by Västerås Löparklubb. Runners choose from 100, 50, 30, 20, or 10 miles, covering distances from a single trail outing to a 100-mile test.
The format uses one 10-mile loop, repeated for the required distance. The 100-mile race is 10 laps, 50-mile is five, 30-mile is three, 20-mile is two, and 10-mile is one lap. The surface varies, including technical trail, running track, gravel walking path, and asphalt bike path. An Instegsultra, an entry-level ultra option, makes the race more accessible than a lineup built only around the longest distances.