Intermediate 100K ultramarathons in United States (South)

Eight out-and-back segments from a central hub, spanning Vero Beach and Sebastian, with tropical waters, jungles, rugged trails, and 22 bridge crossings

Looped cross-country and single track trails with small hills at Mississippi College Choctaw Trails; intense heat and humidity expected

Night-long 100k loop through Talladega Forest on rolling dirt and gravel roads, starting at Frog Pond Overlook, with alternating course direction each year.

Scorching summer heat and technical ranch trails across 1,100 acres at historic 7IL ranch, including 100-mile and 100km ultramarathon relay distances

Flat, mostly grassy 2.5-mile loop with gentle hills at Escambia County Equestrian Center, minimal elevation change and easy crew access

Challenging mountain courses through national forests west of the Shenandoah Valley, featuring fall foliage and panoramic vistas on demanding terrain.

Six-loop, 62-mile single-track course on Meeks Mountain Trails with challenging mountain terrain in Hurricane, West Virginia

Mostly flat and fast out-and-back route on the NETT Trail, mixed terrain with bridge crossings, starting and finishing at Paris's Eiffel Tower.

Challenging, dirty and rocky single and wide track trails with 1400 feet of elevation gain per 15-mile loop at Flat Creek Crossing Ranch near Austin, Texas

Challenging trail run through Palo Duro Canyon with steep elevation changes, vibrant rock formations, and varied surfaces of sand, clay, and sandstone.

10-mile loop on Blue Wing, Koasati, and Whoa Mule trails with flat, muddy paths, tree roots, and views of Lake Bistineau and cypress forests

Rocky ascents and descents along shaded and open trails with lake views at Dana Peak Park; single-loop courses with minimal trail repetition.

Scenic trail loops at High Hope Ranch and Eco-Retreat, combining 3.3- and 7-mile sections for a 10.3-mile lap with moderate difficulty and spaced aid stations.

Rugged gravel and prairie course through Cookson Hills’ oak-hickory forests and valleys, with fall foliage and Illinois River views in the J.T. Nickel Preserve

Technical 20.5-mile figure-eight loop through lush forest, repeated for 100 mile and 100K distances, roots and rocks, strict cutoff time

Forested, rolling hills across 12,500 acres with smooth trails, rocky and rooted sections, and scenic park landscapes

Scenic singletrack along Tellico Reservoir’s eastern shore, lush woods, lakeside viewpoints, out-and-back 100K, approachable terrain, peaceful backcountry vibe

Challenging two-loop course in Cohutta Wildlife Management Area, climbs to Grassy Mountain fire tower, scenic Lake Conausaga, 7,000 feet of elevation gain.

Low elevation 14.35-mile single-track loop course along Wolf River, 7 laps for 100 miles, 34-hour limit, popular Western States qualifier

Scenic single-track loops through Lake Thunderbird State Park with multiple endurance distances and runnable terrain near Oklahoma City