⏵ Course guide · South Carolina lowcountry out-and-back
The Swamp Fox Ultra is the only trail race that spans the entire Francis Marion National Forest, a straight out-and-back through flat lowcountry swamp and pine singletrack, up to 52 miles out for the 100M before you turn around. I will walk you through the course and cutoffs first, then give you a pacing and fueling plan built for a long, flat, humid out-and-back, plus free tools to dial in your own numbers.
These facts come from the official UltraSignup registration page. Course logistics can change year to year, so confirm the current details before you register or run.
Every distance at Swamp Fox is a straight out-and-back, no loops and no repeated shorter out-and-backs, through the Francis Marion National Forest starting near McClellanville.
The 100M covers roughly 52 miles outbound before turning around and retracing the same route. That structure means strategic planning genuinely matters here, since you will not pass a central aid hub repeatedly, and the race's own copy notes the trail feels different once the sun sets and you are heading back through the dark.
The course runs through flat lowcountry terrain, swamp and pine singletrack with boardwalk sections along the Awendaw and Swamp Fox passages of the Palmetto Trail. Without significant elevation change, the challenge here is pure distance, footing over wet or uneven boardwalk sections, and humidity rather than climbing.
The organizer made a deliberate shift toward strategically placed aid stations rather than relying primarily on drop bags, aiming for every participant to get real support along the route. Drop bags are still available and get shuttled to and from aid stations, but plan your race around the aid station network first.
With no significant elevation change but a genuinely long distance and the near-certainty of night running on the 100M and 50M, discipline over the first half is what protects your second half.
Without climbs to force a natural pace check, it is easy to run the outbound leg faster than you can sustain, especially on runnable, flat trail. Set a target pace for the full distance from the start, checked against the 34, 19, or 12 hour cutoff for your distance, rather than letting easy early footing dictate your effort.
The turnaround point on an out-and-back is a natural checkpoint: your outbound split, checked against a finish-time projection, tells you honestly whether your cutoff buffer is real or optimistic. On a course with limited access points, catching a pacing problem at the turn matters more than on a loop course where you pass the start/finish repeatedly.
⏵ Free tools to pace this course
Swamp terrain holds moisture and humidity even when air temperature seems mild, and a long out-and-back through the night on the 100M and 50M adds real fatigue management on top of the heat.
Aim for roughly 60 to 90 grams of carbohydrate per hour, staged around the specific aid stations on the course map since this is not a loop course with constant central access. Know your gaps between stations before race day and pack accordingly.
Keep sodium in the 300 to 700 mg per liter range, leaning higher through the humid lowcountry swamp sections even after dark, since humidity, not just direct sun, drives sweat rate here. Early March in coastal South Carolina can still bring warm, muggy stretches, so do not assume cooler temperatures overnight solve your fluid needs.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a long, humid lowcountry day and night with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a race-day plan built around YOUR fitness, this exact out-and-back distance, and your projected splits. Summit Line reads your real training, builds a plan for a long, humid lowcountry day and night, and rehearses your fueling so race day is something you execute, not guess at.
The terrain itself is flat lowcountry trail, so this is not a vert-heavy ultra. The difficulty comes from distance and exposure: the 100M covers about 52 miles out before turning around and retracing the entire route, through swamp and pine singletrack with boardwalk sections across the full Francis Marion National Forest. With a 34-hour cutoff for the 100M, you will very likely run through at least one full night, and the race's own copy notes the trail "takes on a whole new feel" after dark.
Every distance, from the 10K up to the 100M, runs a straight out-and-back rather than a loop or a repeated shorter out-and-back. That means strategic planning matters: you will need to carry what you need between aid stations on the way out, since you will not pass a central hub repeatedly the way a loop course allows. The organizer emphasizes strategically placed aid stations over relying solely on drop bags for this reason.
The 100M has a 34-hour cutoff from a 7:00 AM Saturday start, the 50M has 19 hours, and the 50K has 12 hours, all also starting at 7:00 AM. The Half Marathon and 10K start later, at 8:00 AM. Given the out-and-back structure and the likelihood of night running on the longer distances, plan your pacing with a real margin against these cutoffs rather than racing them exactly.
With strategically placed aid stations along a point-to-point-style out-and-back (rather than a loop with constant central access), plan your carbohydrate and hydration around the specific aid station spacing on the course map rather than assuming frequent stops. Aim for roughly 60 to 90 grams of carbohydrate per hour and sodium in the 300 to 700 mg per liter range, and account for lowcountry humidity even in early March, since swamp terrain holds moisture regardless of air temperature. Build your numbers with the free ultra fueling calculator before race day.
The flat terrain removes the vert-management challenge that trips up many first-time ultrarunners, which is a real point in its favor. But the out-and-back structure over a genuinely long point of no return (52 miles out for the 100M) and the very real chance of night running mean this still demands solid ultra experience, strong navigation and pacing discipline on flat trail, and a fueling and hydration plan built for lowcountry humidity, not just raw fitness.
The race describes itself as the only trail race that spans the entire Francis Marion National Forest, combining the Awendaw and Swamp Fox passages of the Palmetto Trail into a single continuous out-and-back. That gives you a genuinely rare, extended tour of South Carolina lowcountry wilderness, swamp, pine forest, and boardwalk crossings, in a single event rather than a shorter loop confined to one corner of the forest.
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<a href="https://runsummitline.com/guides/swamp-fox-ultra">The The Swamp Fox Ultra course guide</a><iframe src="https://runsummitline.com/embed/race/swamp-fox-ultra" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="The Swamp Fox Ultra course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.