12hr ultramarathons in California, United States

Looped 1.3-mile course featuring trail, grass, and bike path segments in Montgomery Waller Community Park, near Imperial Beach and Chula Vista

Scenic loop route on dirt fire trails with modest elevation gain and classic trail ambiance

Time-based ultrarun in Napa's Skyline Wilderness Park, 4.16-mile trail loop with 815 feet of gain per lap through rolling hills and historic landscapes

Trail route through Mendocino Woodlands State Park with forest scenery, tent cabin options, and meals included on Saturday

Looped 0.85-mile paved bike path through scenic Auburn, with picturesque ponds, shaded stretches, and multiple distance options

1-mile loop on private desert land near Joshua Tree, 12-hour format, high desert scenery, festive atmosphere, well-stocked aid each lap

One-mile hard-packed dirt loop with direction changes every four hours, frequent aid stations, and personal camp support throughout timed ultra options.

Varied Skyline Park trails with multiple 4.1-mile loops, 815 feet of elevation gain per lap, fire roads and singletrack, run at own pace

Time-based ultrarun in Napa's Skyline Wilderness Park, 4.16-mile trail loop with 815 feet of gain per lap through rolling hills and historic landscapes

Looped golf course circuit with rolling fairways, cart paths and lakeside stretches, framed by Sierra foothills and Central Valley orchards.

2-mile double track dirt loop with 128 feet of gain per lap, mountain desert scenery, starlit night running, camping on-site, real bathrooms and aid station

Challenging 4.6-mile loop on private trails near Baum Lake, surrounded by fall foliage, wildlife, and scenic views

Timed distance ultramarathon on a 1-mile paved loop at Mary Grogan Community Park during the winter solstice

Flat 1-mile loop on 100% hardpacked dirt, set on a Southern California fruit and nut farm with close access to aid, crew, and vehicles.

USATF-certified 1.0-mile loop around Cottonwood Lake with lake views, challenging endurance events including 24 Hour Solo and 100 Mile distances

12-hour overnight race on a one-mile loop, with rest and refuel zone at the start area and flexible pacing for runners of all levels

Rolling 2-mile loops through Will Rogers State Park, gentle terrain, multiple laps, fully stocked aid station, solo and relay formats, 24- and 12-hour options

Mountain venue along Lake Cuyamaca at 4,613 feet elevation, surrounded by scenic views just south of historic Julian

One-mile loop course in a 20-acre desert near downtown Joshua Tree, featuring solo stretches, festival ambiance, and personal rest space for participants