The San Lorenzo River Trail Run begins and ends at Harvey West Park's Friendship Picnic Area in Santa Cruz, California. Trail distances offered are 10K, half marathon, 30K, marathon, and 50K, in addition to a free Kids Run for children six and under. Bib and shirt pickup on race day starts at 7:00 a.m. Participants should arrive 45 minutes before their scheduled start time. Each distance has a 9-hour completion limit. This event is a dirt-and-trail race, not a road race. Routes are measured by surveyor's wheel and marked with colored ribbons: yellow for the 10K, pink for the half marathon, pink with an orange loop for the 30K, two half-marathon laps for the marathon, and the 30K route plus the half marathon for the 50K.
The course winds through coastal redwoods, some reaching 300 feet tall and approximately 1,500 years old. It then proceeds through stream canyons, open meadows, pine and oak forests, and chaparral ridges. The half marathon, 30K, marathon, and 50K routes cross the San Lorenzo River multiple times. This connects the race to the 29.3-mile river that originates high in the Santa Cruz Mountains, descends sharply near its headwaters, flows through the San Lorenzo Valley, and empties into Monterey Bay at Santa Cruz. Polka-dot flags indicate turns, and blue ribbons signal incorrect paths. Passing etiquette is straightforward: announce "on your left" when overtaking another runner or hiker. Headphones are permitted only on dirt road sections, suitable for a course where runners share narrow trails with others.