Sean O'Brien 100K

The Anytime Runners 12H Training Run is a supported endurance event held at Griffith Park, Los Angeles, specifically at the Crystal Spring Picnic Area. Participants run or walk on a mostly flat 3-mile loop trail for up to 12 hours, from 6 AM to 6 PM, with the flexibility to start anytime between 6 A..

Tough Mugu is a challenging trail running event held at La Jolla Group Campground in Point Mugu State Park, Malibu, California. It features two main distances: a 25k and a 10k course, both showcasing Southern California's stunning coastal mountain trails. The 25k course covers 15.75 miles with 2,427..

The SoCal Summer 6K/12K, hosted by Pasadena Running Company, is a trail running event held at Lower Arroyo Park in Pasadena, California. Scheduled for a summer Friday evening, it offers two distance options: a 6K (3.9 miles) and a 12K (7.8 miles, two loops of the 6K course). The course features mixe..

The Bulldog Ultra, held in Malibu Creek State Park, Calabasas, CA, is Southern California's oldest 50k trail race, celebrating over 30 years. Scheduled for August 16, 2025, it offers two distances: a challenging 50k ultra with 29.4 miles and 5,784 feet of elevation gain, and a 25k trail run covering..

The No Name Trail Races, now known as the Cheeseboro Canyon Trail Run, take place in Cheeseboro National Park, Agoura, California, within the Santa Monica Mountains National Recreation Area. The event offers multiple distances including a challenging 50K ultra marathon with nearly 5,000 feet of elev..

No Name 5025 is a trail running event held at Cheeseboro National Park in Woodland Hills, California. It features a challenging 50k ultramarathon, along with a half-marathon, 5k, and a kids’ 2k fun run. The course offers diverse terrain, including runnable ascents, winding singletracks, steep fire r..