Chasing Cutoffs - Sean O'Brien 100k Ultramarathon

The Sean O’Brien 100K is one of Southern California’s signature ultramarathons—an iconic, punishing, and breathtaking footrace carved into the rugged spine of the Santa Monica Mountains. Held each winter, the 2025 edition brought runners face-to-face with steep climbs, technical singletrack, exposed ridgelines, and sweeping Pacific Ocean views that make every mile unforgettable. In this video, I take you inside the full race experience: from the pre-dawn start line energy to the relentless climbs, the infamous Bulldog section, aid station highs (and lows), and the mental battle that unfolds over 62 grueling miles. Expect honest commentary, course insights, and the raw reality of what it takes to finish one of the most challenging ultramarathons in the region. Whether you’re training for the Sean O’Brien 100K in 2026, considering signing up in the future, or just love following endurance adventures, this video will give you a true runner’s-eye view of the race—its beauty, its brutality, and the big payoff waiting at the finish line. If you're thinking about running SOB 2026, this is your inside look at what to expect. #ultrarunning #seanobrien100k #endurance #trailrunning #ultramarathon 00:00 - Intro 00:30 - Morning of the Sean O'Brien 100k 01:19 - Start line 02:07 - Sun starting to rise 03:06 - Meeting new people on the trail 04:20 - First aid station (Corral Canyon) 05:06 - Mile 10 update 06:30 - Second aid station (Kanan) 07:08 - Funny signs on the course 07:52 - Third aid station (Zuma) 08:31 - Climbing and then descending towards Bonsall 08:43 - Mile 20 update 09:44 - Fourth aid station (Bonsall) 10:19 - Long climb out of Bonsall 12:10 - Fifth aid station (Zuma #2) 12:48 - Back on the trail 13:30 - Sixth aid station (Kanan #2) 14:17 - Talking about a random trail interaction 15:28 - Mile 36 update 16:34 - Seventh aid station (Corral Canyon #2) 16:46 - Not dropping down to 50 miler 17:23 - Mile 42 update 18:05 - Passing through MASH filming site 18:58 - Leaving eighth aid station (Bulldog turnaround) 19:16 - Headlamp running in the dark 19:41 - Nineth aid station (Corral Canyon #3) 20:30 - Running towards the finish 20:53 - Crossing the finish line