About 1,000 runners are expected to take Sunday to man-made mud pits Sunday on the Coast Guard Training Center at Two Rock for the first staging of the MudMan run.
Participants choose between 6.1- and 3.5-mile courses, as well as a 1-mile kids' course. There are competitive and just-for-fun categories.
Runners will tackle a variety of terrain and obstacles, but will inevitably find themselves in at least one of three deep, bulldozer-created mud pits, organizers said.
The event is run by the team behind the annual Vineman triathlons. Donations collected in the parking lot will support the Two Rock Union School physical education, art and music programs, said Principal Mike Simpson.
About 140 volunteers, including Coast Guard members and civilian employees, as well as school staff, are expected to support the event.
Races begin at 9 a.m. with the final award ceremony at 12:30 p.m.