Bonneville Salt Flats, UT. Endurance ultramarathon events with the mind-bending terrain of the Salt Flats, Island Mountains, and Mud Flats surrounding the Bonneville Speedway.  The weather at this time of year can be everything from sunny and low 80s to blowing snow and low 20s.  Finish under the 36-hour cutoff, and the coveted SF100 Buckle is yours!