Marin Ultra Challenge

Race Description

Our premier Marin County long distance trail race, the MUC delivers ample hills and sweeping descents. This year marks the 11th edition of this tour of some of Marin’s best trails. Meticulous effort went into the design of each course for the MUC; both distances are physically demanding (the 50 Mile has just about 11,000 feet of elevation gain) and exceptionally beautiful. The journey begins at the black sand of Rodeo Beach, then traverses the Marin Headlands, Stinson-facing Mt. Tamalpais and Muir Woods, exhibiting a range of terrain, from exposed fire-roads with incredible coastal and inland views to tight, technical single-track with redwood canopies. There is very little trail overlap, and Jim Vernon, from The Endurables and Hydrapak, spent hours and weekends developing these spectacular custom courses–we are super excited to show it off. You’ll quickly realize why Marin County has become the ultimate trail runner’s destination.

Race Information

Marin Ultra Challenge 2026 Runner's Guide Location: Marin Headlands, Muir Woods & Mt. Tamalpais State Park Date: Saturday, March 13, 2027 Events: 50K & 50 Mile Early Bib Pickup @ San Francisco Running Company - Mill Valley: Friday, March 12; 1:00 PM - 6:00 PM Race Morning Bib Pickup: 6:00 AM - 7:00 AM Start Times (Subject to change at the park's discretion): 50 Mile March 14 @ 6:30 AM 50K March 14 @ 7:00 AM Timing: We will be partnering with ultralive.net for timing, aid station tracking and splits. There is a $3 fee added to race entry this year to bring this amazing feature to you! Time Limit: There is a 14 hour time limit for the 50 Mile race. There is a 10 hour time limit for the 50K. All runners must be off the course by 8:30 PM Parking: Free parking is available in the surrounding areas to the Start/Finish at Rodeo Beach. Runners may utilize the pullouts along Mitchell Road, along the beach, the annex lot below the Marine Mammal Center, and the Smith Road Parking Lot (Gerbode Valley Trailhead) along Bunker Road. The walk from the Marine Mammal Center lot to the Start/Finish is about 1/3 mile. The later you arrive the further you may have to walk to the Start/Finish, so please plan your arrival time accordingly. Race Capacity: The Marin Ultra Challenge will have a capacity of 500 runners, across all distances.

50/50 Challenge

50/50 Challenge Are you interested in participating in our third annual 50/50 Challenge (Monterey Ultra 50 Miler and Marin Ultra Challenge 50 Miler)? You will get on our 50/50 leader board and all finishers of the 50/50 get a commemorative Victory Sportdesign Gear Bag! Registration for the 50/50 Challenge is part of our Monterey Ultra Registration, the first race the the 50/50 Challenge. Cancellation notice: to receive a credit must be 3 weeks out from either event you are withdrawing from.

Volunteer

Without the support of enthusiastic and caring volunteers producing our races would not be possible. Volunteers of all ages and abilities help with setup, check-in, aid stations, course marshaling, timing, and post-race food. Volunteering is a fun, novel way to experience races, play in the outdoors, and spend time with friendly people. All volunteers receive a free race T-shirt, free food, and the ability to earn credit toward a future Inside Trail Racing event, commensurate to the amount of time worked. Five hours of assisting an event results in a free race credit or Inside Trail merchandise. To volunteer for this year’s event, please submit our online volunteer form .

Aid Stations

Inside Trail Racing aid stations are replete with an optimal variety of glycogen-replenishing, electrolyte-replacing products. The following is a list of some of the foods and beverages each aid station may provide: Gu Energy gels (Note: GGNRA does not allow Gu Gels at aid stations on their property: Conzuleman, Tennesse Valley, Muir Beach, and Willow Camp), chews, and Stroopwafels, trail mix, pretzels, potato chips, Oreo cookies, boiled potatoes with salt, Coke, Ginger Ale, water, Skratch Hydration Mix, PB&J sandwiches, M&M’s, salt tablets, bananas, watermelon, and tangerines. Aid stations are also equipped with general first aid items, including Salt-Stick tablets, but no anti-inflammatory medicine. Skratch Hydration is mixed so that it contains 80 – 100 calories per 20 fluid ounces. As distances between aid station vary, we strongly encourage all runners to carry at least one 20oz bottle during their run.

Course Information

50 Mile & 50K 50K and 50 Mile Course Map - GGNRA | 50K and 50 Mile Course Map - Mt. Tam 50 Mile - Turn by Turn Directions | 50 Mile - Aid Station Distances and Cutoffs | 50 Mile Elevation Charts 50K - Turn by Turn Directions | 50K - Aid Station Distances and Cutoffs | 50K Elevation Charts Sunrise for Sausalito, CA: 7:21 AM Sunset for Sausalito, CA: 7:16 PM Drop Bags and Headlamps Any runner who expects to be running beyond 7:16 PM should plan on having a headlamp in one of their drop bags. Drop bags will be available at 2 different aid stations (which the 50 Mile will pass a total of 4 times, 50K runners will pass 2 times): 1) Tennessee Valley AS: Mile 10.5 2) Cardiac AS: Mile 19.8 (50 Mile Only) 3) Cardiac AS: Mile 29.3 (50 Mile Only) 4) Tennessee Valley AS: Mile 45.8

Volunteer

For 2026, MUC Volunteers will be getting a custom "MUC Trail Support" Shirts. Don't forget to include your size! We will need to order these 2 weeks prior to the event to get in your desired size. Without the support of enthusiastic and caring volunteers producing our races would not be possible. Volunteers of all ages and abilities help with setup, check-in, aid stations, course marshaling, timing, and post-race food. Volunteering is a fun, novel way to experience races, play in the outdoors, and spend time with friendly people. All volunteers receive a free race T-shirt, free food, and the ability to earn credit toward a future Inside Trail Racing event, commensurate to the amount of time worked. Five hours of assisting an event results in a free race credit or Inside Trail merchandise. To volunteer for this year’s event, please submit our online volunteer form .

Shirts

Most of our race shirts are District Perfect-Tri tri-blend fabric shirt. This tee is made with top-of-the-line sportswear technology to heighten performance during your toughest workouts. With sun defense, moisture-wicking technology, quick stain release, and comfortable fit, this tri-blend performance crew serves the needs of every athlete. It’s the perfect year-round choice for outdoor sports and exercise. Get the most out of your workout with this tough, hardworking tee. Features: ● 4.5-ounce, 50/25/25 poly/combed ring spun cotton/rayon, 32 singles ● 1X1 rib knit neck ● Shoulder to shoulder taping ● UPF 30 To be guaranteed a shirt and shirt size, you must register by February 27, 2027.

Awards

Overall winners of each race distance will receive a custom MUC award. The top 3, male and female, finishers in the 50 Mile event will receive a custom trophy, as well as the following cash awards: ● 1st - $1,000 ● 2nd - $500 ● 3rd - $250 All 50 Milers will receive a custom medal with the race logo and a Boco Trucker Hat. The top 3, male and female, finishers in the 50K event will receive a custom trophy, and an entry into a future iTR event (50K in value). All 50K finishers will receive a medal and a custom printed drinking glass with the race logo. The Dead Last Finisher (DLF) in each even will receive a custom award. Age-group medals (3 deep) will be awarded in the following categories, for males, females, and non-binary: ● 13 and under ● 14 – 19 ● 20 – 29 ● 30 – 39 ● 40 – 49 ● 50 – 59 ● 60 – 69 ● 70 and over

The Fine Print

ITR Refund Policy: Entry fees to our trail runs are non-refundable in all cases, and we do not offer credits, transfers, or deferrals to future races except as described below. Only registered runners can participate in our races, and you cannot exchange your entry with anyone else in any case. We are happy to issue a credit worth 50% of your original race fee toward a future Inside Trail Racing event if we receive your cancellation at least 3 weeks prior to the race. Credits will expire 1 year after the date issued. There will be no credit provided if a cancellation is made within 3 weeks of the race. While we understand that last-minute injuries, conflicts, emergencies, deaths, and other unfortunate events affecting registered runners can happen and may impact your plans for participation, we must adhere to our cancellation policy stated above and cannot offer any credits, refunds, transfers, or deferrals in any of these cases. If the situation does arise where ITR must outright cancel an event for any reason, there will be no refunds. This could include earthquakes, floods, extreme weather, unsafe air quality, pandemics, or any other “Act of God”. ITR at its sole discretion may choose to offer future race credit or deferrals in these force majeure situations, depending on the circumstances and how close to the race date the event was cancelled. We will communicate with all registered runners as soon as possible regarding the cancellation and any pertinent information. We do not cancel races due to rain or heat. Due to trail work, closures, or for myriad other reasons, permitting agencies may require changes to the publicized courses at any time prior to an event. This is out of our control, and we therefore will not offer refunds, credits, deferrals, or transfers (except as described below) in such a situation. If a race location is changed, but still hosted on the same day, we will automatically transfer the registration over to the new venue, or entrants may choose to run the race remotely and we will mail awards. If a race is postponed all entrants will be transferred to the new date. www.insidetrail.com