The course
The Tamalpa Headlands 50K is a single loop out of Santos Meadow near Muir Beach, and it strings together a bunch of the well known Marin trails: Coastal, Miwok, Marincello, and the Dipsea. The official 2026 route measures 31.3 miles with 7,061 feet of climbing and just about the same amount of descent. You bounce between fast fire road, flowy singletrack, and steep technical steps the whole way around. The course was updated for 2026, confirmed directly by the race director: the old Matt Davis descent is gone, and the new route crosses Rodeo Beach on the sand and finishes its climbing with a Dipsea out-and-back off Cardiac.
Headlands ridgelines and the early miles
The early miles take you through the Marin Headlands on the Coastal and Miwok trails, rolling over exposed ridgelines with big ocean views. The 2026 course crosses Rodeo Beach itself on the hardpack sand, a nod to where the classic course used to start, so expect a short honest stretch of beach running in there. The footing is good through most of this, a mix of fire road and runnable singletrack, and that is exactly why you want to push. That is the trap. You spend your climbing legs early on the stuff that feels easy, and the real climbs up Mount Tam come back to collect.
On the way to Tennessee Valley the route now takes a short, sharp little climb on Miwok before jumping onto Marincello for the descent in. It is a quick punchy grade, the kind that spikes your heart rate if you attack it. Run these opening miles by effort, not by pace. Find a rhythm you could hold for hours, hike the steeper bits with a purpose, and let everyone else sort themselves out. You want fresh legs for the back half, because that is where this race is decided.
Cardiac twice, and the Dipsea turnaround
The meat of the course is the climbing toward Mount Tamalpais, and the 2026 route hits Cardiac twice. The first pass takes a small loop around Pantoll Ranger Station. The second pass is the one that decides your race: you drop down the Dipsea, steep stepped technical trail that wants careful feet, turn around at Panoramic Highway, and then climb straight back up to Cardiac. That last climb comes late in the day on tired legs, and the race director himself says it will challenge everyone. Believe him.
These are long grinding climbs, and strong efficient power hiking will do more for you than trying to run every step. Climb by grade and by your breathing, not by a number on your watch. A steady hiking effort up Cardiac that you could repeat will leave you a lot better off than a hard surge, because you are going to need that exact climb again.
The descents are where legs go to die
The course drops almost as much as it climbs, so the downhills are the real problem, not the climbs. The Marincello drop into Tennessee Valley is fast and will tempt you to open up early, and the Dipsea descent off Cardiac is rooty, stepped, and technical, including a staircase pitch near Steep Ravine that drops at close to a 30 percent grade, and it will wreck quads that never trained to go downhill. The Dipsea drop has a catch built into it too: you turn around at Panoramic Highway and climb right back out, so anything you smash on the way down you pay for on the way up, immediately.
Run the descents controlled and light, especially early on. Hold a little back on the Dipsea in particular, knowing you need something in the tank for the climb out. Quad-specific downhill training in your build is some of the most useful work you can do for this course. It is the difference between still running late and walking like your legs are made of glass.
Coastal conditions and exposure
August in coastal Marin is a coin flip. The morning can start cool and foggy near the coast, then burn off into real sun on the open ridgelines by midday. Do not let a gray, mild start trick you into under-drinking, because the open climbs can get warm and sunny even when the beach is socked in. And do not over-dress for fog that is going to lift on you.
The shaded forest in the creek canyons gives you a break, but the ridgelines and the Mount Tam climbs are where heat will get you. Keep your fluid and sodium steady the whole way, and adjust as the marine layer comes and goes.
Aid stations and cutoffs
The loop is supported by aid stations at the major trail junctions, with checkpoints at spots like Tennessee Valley and Cardiac. The bigger ones have food, fluids, and crew-friendly access. The overall time limit is 10 hours, with a finish cutoff around 5:30 PM from the 7:30 AM start. The course changed for 2026, so check the current aid chart rather than an old year’s.
A few of the intermediate cutoffs along the way are firm, so you cannot just casually hike the front and middle of the race. Pull up the official Headlands 50K cutoff chart for the current year and build your plan backward from those times, with a buffer. The climbing and the technical descents both slow you down as the day goes on, so give yourself room.
Pacing strategy for the Tamalpa Headlands 50K
A steep technical 50K with this much vert rewards patience and punishes ego. Pace it by effort and by grade, not by the flat-ground numbers from your home training runs.
Pace the climbs by grade, not by clock
On a 50K with over 7,000 feet of gain, your moving pace is going to swing all over the place between the climbs and the runnable ridgelines, and that is fine. Power-hike the steep stuff efficiently, especially the long Cardiac pulls and the Dipsea steps, and run the gentler grades. Trying to hold one steady minutes-per-mile number across this terrain is the quickest way to cook the climbs and show up at the descents with nothing left.
Use our free grade-adjusted pace calculator to turn your flat fitness into honest effort targets for the steep Tamalpa climbs. Then you actually know whether you are pacing the vert in a way you can hold, or burning matches you are going to want late in the loop.
Protect your quads for the descents
The course loses nearly as much as it climbs, so downhill running is the thing that makes or breaks your day. Hold back on the early descents, run them controlled and light instead of letting gravity hammer your legs, and your last climbs and drops will be so much better. The people who finish strong out here are almost always the ones who still have working quads at mile 25.
To set a finish goal that actually accounts for all that vert, use our vert-aware race time calculator. It builds the climbing into your projected finish so you are not stuck on a flat 50K estimate that the Mount Tam climbs are going to quietly destroy.
Respect the cutoffs and the conditions
With a 10 hour limit and firm intermediate cutoffs, you need some margin in the front half, but not if it costs you the whole race. The smart move is a controlled effort you can repeat, one that keeps you comfortably ahead of every checkpoint while you protect your legs for the technical back half. And keep an eye on the marine layer, because a sunny midday ridgeline can slow you down more than you would think.
If you want to know how your fitness from a recent race lines up with a climbing 50K like this, our race equivalent calculator lets you sanity-check your goal time before you commit to it.
Fueling strategy for the Tamalpa Headlands 50K
A 5 to 9 hour effort over steep terrain makes fueling and hydration matter as much as fitness. The coastal weather is the thing that catches fit, well-trained runners out, so plan for fog and sun both.
Carbs: aim for a trained gut, not a heroic number
For most finishers in the 5 to 9 hour range, aim for roughly 60 to 90 grams of carbohydrate per hour on a gut you have trained to take it. Use a glucose-plus-fructose blend so you can absorb more than one sugar alone lets you, and practice your exact hourly carb number on long hilly training runs so it feels normal on race day, not like an experiment. Faster runners sit toward the low end of the time and may need fewer total grams, but the per-hour habit still matters.
The steep climbing makes eating harder, because when the effort spikes your appetite drops. So practice taking in calories while you power hike. Keep nibbling through the Cardiac climbs even when you really do not feel like it.
Sodium and fluid: don't trust the fog
Coastal Marin can start cool and foggy and then turn sunny and open, so do not under-drink off a mild morning. Sodium around 400 to 700 mg per liter of fluid covers most runners, and you push higher if you are a salty or heavy sweater or the day turns warm up on the ridgelines. Cramping, a sloshy stomach, and that wrung-out late-race feeling are usually fluid and sodium problems, not fitness problems. Honestly, most blow-ups out here are.
Dial in your own plan with our free ultra fueling calculator. Put in your weight, your goal time, and the conditions you expect, and it gives you a carb, sodium, fluid, and caffeine number per hour built for this 50K. Then go test it on a steep training run, not on race day.
This guide is for planning and training purposes and reflects publicly available information about the Tamalpa Headlands 50K. Race details, including the date, course, aid stations, and cutoffs, can change year to year. Always confirm the current specifics on the official Headlands 50K race website before you train or travel.