Great Springs Trail Race - Natural Bridge Caverns

Event overview

The Great Springs Trail Race at Natural Bridge Caverns takes place on September 26, 2026 at 26495 Natural Bridge Caverns Rd, San Antonio, TX. Distances and divisions include:

• 4 mile
• 8 mile
• 16 mile
• Last Person Standing Run
• Last Person Standing Ruck
• 8 mile Ruck
• Youth 1 mile (ages 12 and under)

The regular distance races start inside the Natural Bridge Caverns, part of the Comal Caverns network, with an initial quarter mile underground. Last Person Standing participants do not start in the cave; they receive a Discovery Tour pass and can earn a Hidden Wonders Tour pass by finishing the 24th lap.

Course, format and logistics

Last Person Standing format uses a repeating loop: run laps are 4.1667 miles and ruck laps are 2.47 miles. Laps begin every hour; a competitor must complete the loop in under 60 minutes to continue. Missing the hourly cutoff removes a competitor from the event. Pacers are not allowed.

The course is marked with orange caution tape, yellow arrow signs, and confidence markers. One aid station is on course for the 16 mile race. A full aid station at the start/finish/next-lap arch offers fruit, sandwiches, water, Tailwind, snacks, and at night hot foods and cold sodas. The event is cupless; participants must bring a cup or buy a collapsible cup at packet pickup.

Ruck division rules require mandatory weigh-in and specific pack weights: 20 lb if under 150 lb, 30 lb if over 150 lb. Weight must be on the back and not consumable. Chip timing uses ankle chips; chips must be returned if a runner leaves the race. Drop bags are not allowed on course but are permitted at the race hub. Parking is available 200-600 yards from the hub; there is no on-site camping. Visit the organization's website for the most recent information.