OTILLO Swimrun Austin

Austin Solstice Circuit Challenge

The Fastest Summer Ultramarathon in Texas

July 25 & 26, 2026 | Pace Bend Park, Lake Travis

Set a PR!

Scenic Hill Country Course

Experience the breathtaking beauty of the Texas Hill Country as you run on smooth paved roads winding through majestic oak trees. With Lake Travis as your backdrop, this picturesque route combines natural beauty with the perfect running surface for speed and comfort.

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Set your sights on a personal record at the Austin Solstice Circuit Challenge. This unique event features a perfectly engineered 1.64-mile paved loop with an elevation gain of just 33ft at scenic Pace Bend Park on Lake Travis, designed for speed and performance even in July.

Race Distances

52.7 Mile Race

Loops: 32

Distance: 52.7 mi

Start: 7:00 PM 07/25

50K

Loops: 19

Distance: 31.0 mi

Start: 7:00 PM 07/25

Marathon (USATF Certification code: TX25015LAB)

Loops: 16

Distance: 26.35 mi

Start: 7:00 PM 07/25

25K

Loops: 10

Distance: 15.5 mi

Start: 7:00 PM 07/25; 7:00AM 07/26

10K

Loops: 4

Distance: 6.2 mi

Start: 7:00 PM 07/25;

7:00 AM 07/26

5K

Loops: 2

Distance: 3.1 mi

Start: 7:00 PM 07/25

7:00 AM 07/26

Carpe Diem 60

One Hour. One Sunrise.

Beat the heat.

Seize the morning.

Earn your day.

Start: 6:00 AM 07/26

7:00 AM 07/26

Why Choose This Race?

Fast, PR-Friendly USATF Certified Marathon Course (Boston Qualifier)

Unlike typical Texas summer ultras with brutal heat and technical trails, our smooth asphalt loop with minimal elevation gain creates ideal conditions for record-setting performances. This is a USATF-certified course: Certification code: TX25015LAB.

Evening Start Format

Race as the sun sets and July's magnificent Buck Moon rises over the limestone bluffs. Our strategic evening start times for longer distances mean cooler temperatures when you need it most.

Pacers Allowed

While we won't be providing official pacing groups for the Austin Solstice Circuit Challenge due to our size, we enthusiastically welcome personal pacers for both the Marathon, 50K and 52.7 Mile Solo events. Personal pacers can join Marathon and 50K participants after 8 loops and 52.7 Mile runners after 16 loops (approximately halfway points). Each pacer must pay a $15 fee that covers park entry, administrative costs, and an official pacer bib. Pacers need to sign a waiver and wear their designated "PACER" bib while on course. Runners are responsible for arranging their own pacers, but the loop format makes it particularly convenient for your support crew to join when you need them most. We find this flexibility is especially appreciated by first-time marathoners and ultra runners who benefit from personalized support during the challenging later miles as day turns to evening.

Pickup Information:

Saturday Packet Pickup:

Available from 4:30 PM to 6:30 PM.

Race Day Pickup:

For those unable to attend on Saturday or who prefer to pick up on race day, same-day packet pickup will be available Sunday morning from 5:30 AM to 6:30 AM.

Carpe Diem 60

One Hour. One Sunrise. Start your day with purpose.

Carpe Diem 60 is a 60-minute sunrise endurance challenge on this out-and-back course. At 6:00 AM, you’ll have one hour to cover as much distance as possible with early morning focus. Most Distance Covered Wins

Beat the heat. Seize the morning. Earn your day.

Course Details

The distinctive figure-8 course winds through the breathtaking Hill Country landscape of Pace Bend Park, featuring limestone bluffs, majestic oak trees, and views of Lake Travis. The smooth asphalt surface throughout makes it perfect for both day and night running, with the main loop connecting to a smaller upper loop.

• Surface: 100% smooth, paved asphalt – ideal for consistent pacing

• Elevation: Minimal gain per loop – gentle, predictable terrain

• Loop Length: 1.64 miles in a figure-8 configuration

• Scenery: Limestone bluffs, oak-covered hills, and Lake Travis views

• Aid Station: Access every 1.64 miles at the start/finish hub

• Marking: Fully marked with reflective markers for nighttime visibility

"Whether you're chasing a PR, a qualifying time, or simply want to experience the joy of running fast through a Texas summer night beneath towering oaks and limestone cliffs, the Solstice Circuit Challenge offers a rare opportunity to push your limits under optimal conditions."

Amenities

Aid Station

Fully stocked station at the start/finish hub

Restrooms

Convenient toilet vault facilities

Camping

First-come, first-served sites surrounding the course

Parking

Multiple areas for easy access

Finisher Awards

Medals and custom challenge coins for all finishers

Commemorate your achievement with a premium custom-designed medal featuring Lake Travis. These coins are part of the Race Austin Series: Collector's Challenge, which allows you to exchange three same-tier coins from different Fit Foundation races for a complimentary race entry of the same tier.

Race Austin Coin Challenge Race Austin Coin Challenge Race Austin Coin Challenge

Join Us for an Unforgettable Experience

Race from sunset to stars beneath the Buck Moon on the fastest summer ultra course in the Texas Hill Country.

REGISTER NOW!

Ready to prepare? Check out our comprehensive training guide designed specifically for the Solstice Circuit Challenge.

August 8th, 2025.

This is the culminating event in the Capt'n Karl's Trail Series at one of the best privately owned adventure parks in all of Texas, the amazing Reveille Peak Ranch! This park is located 55 miles northwest of Austin in the historic town of Burnet. The amenities at RPR are first class & we will be taking advantage of this by providing our runners, spectators & volunteers with a series finale party. But first, runners will be treated to unique & spectacular geological formations. Navigating over large rock domes with amazing views, while tackling the most elevation gain of our four venues (3812 ft). This course really has it all….single track, exposure, tree-covered woods, hills & technicality. All to challenge even the most seasoned trail runner.

While every racer will get some cool swag, July 16th is the deadline to get a shirt.

Join us for the annual Summer Sizzler 5k/10k/15k! A fun summer event that is perfect for the whole family.

The fun includes -

• Great Swag - designer shirt & custom medal

• Chip-timing with live results and awards

• Free photos

• Delicious Treats waiting at the finish line

• FREE Kona Ice!

• Plenty of fun!

Grab your friends and family, you are not going to want to miss this one!

Can't make the race? No problem! We offer a virtual race option where you can run anywhere, at any time, and still earn the fun swag!

*Youth-based pricing for the 5k/10k, 12 & Under are only $17!

• 5k/10k/15K registration includes a custom bib, designer shirt, and a custom finisher medal!

• 1 Mile registration is untimed and includes a custom bib, designer shirt, and a custom finisher medal!

• The kid's dash is a fun, untimed dash for our kiddos ages 10 and under. Registration includes a mini bib, youth-sized shirt, and a specifically crafted medal for our kids' dash event! (If your child wants to run the kid's dash, and doesn't want the SWAG, they are welcome to run with us on race day for free!)

*Register by midnight on Thursday, two Thursdays before race day, to guarantee your shirt!

🏁🏅Create a team, or join an existing team during registration. Once 4 people have registered on that team, all team members will be refunded $5, once ten people register another $5 will be refunded for a total of $10!

September 12, 2026.

Get your friends and family, and join in on this close to Austin and San Antonio lake party and trail run! The finish line arch will be as close to the edge of Lake Travis as we can get it (Austin area’s famed lake boasting over 9 miles of shoreline)! So when you finish you can cruise straight into the water to cool off and start your floating post-race party! This means, as the lake rises and falls each year, the distance will possibly slightly change, so we'll add "ish" to each distance...and that's perfect when everything and everyone stays mellow.

We’re incredibly thankful for the support of this race by the Travis County Parks Foundation!

While every racer will get some cool swag, August 18 is the deadline to get a shirt.

During registration, we are collecting $10 for one day of access to the park. If runners are staying for more than one day, they will have to pay additional amounts upon entering the park.

Click Here for Tejas Trails Policies (you really do want to know this stuff)

COLORADO RIVER RUN

Run to the River

"Out here on these trails, not all who wander are lost, some are simply finding their strength."

100 MILES

50 MILES, 10 MILES & 5 MILES

50K & MARATHON

HALF MARATHON

10K & 5K

An invigorating trail adventure at Turkey Bend Park

Connect with Nature, Challenge Your Endurance

Set along the scenic banks and trails surrounding the majestic Colorado River at Turkey Bend Park, this event offers a unique opportunity to connect with nature while testing your limits. Run through diverse landscapes, including riverbanks, rugged trails, and serene natural habitats as you embrace the spirit of outdoor adventure.

The Colorado River Run promises to be a memorable experience for runners and nature enthusiasts alike. The course layout is designed to highlight the river's most picturesque spots while providing a challenging terrain for runners of all levels, from competitive athletes seeking to set personal records to recreational runners looking for a unique trail experience.

Register by November 7, 2026 to guarantee your race shirt!

Reserve an 8-person camping spot here

Race Distances

100 Mile Ultramarathon

Start Time: 8:00 AM

Cut-off: 39 hours

The ultimate river trail adventure for endurance athletes

50 Mile Ultramarathon, 10 Miler, 5 Miler

Start Time: 8:00 AM

Cut-off: 36 hours

Challenge yourself with breathtaking river views

50K & Marathon (26.2 miles)

Start Time: 8:30 AM

Cut-off: 12 hours

Classic distance with unforgettable scenery

Half Marathon (13.1 miles)

Start Time: 8:30 AM

Cut-off: 9 hours

Perfect distance to enjoy the river trails

10K (6.2 miles) | 5K Run/Walk (3.1 miles)

Start Time: 8:30 AM

Cut-off: 9 hours

Family-friendly option - children can accompany registered parents for free!

Course Description

Scenic River Trails

The course is designed to highlight the Colorado River's most picturesque spots while providing a challenging terrain for runners. You'll experience diverse landscapes, including riverbanks, rugged trails, and serene natural habitats.

Fully Supported Adventure

Fully stocked aid stations along the course, providing hydration, nutrition, and medical assistance to ensure your safety and well-being. Our eco-friendly practices, such as waste reduction and the use of sustainable materials, minimize the event's environmental footprint.

What You'll Experience

• Terrain: Mix of single-track trails, dirt paths, and occasional technical sections

• Scenery: Stunning river views, natural habitats, and diverse ecosystems

• Elevation: Moderate with some challenging climbs and descents

• Support: Well-stocked aid stations with friendly volunteers

• Community: Welcoming atmosphere for runners of all abilities

Ready for 100 Miles?

Access your complete 100-mile training plan to prepare for this epic adventure!

ACCESS TRAINING PLAN

What's Included

Custom Finisher Medal

Unique medal for all finishers

Aid Stations

Fully stocked with nutrition and hydration

Support

On-course and at finish line

Pacing Allowed for Ultra Distances

Pacers are allowed for the 100 Mile Run (after mile 50) and 50 Mile Run (after mile 30) to provide safety and encouragement during later stages. One pacer per runner is permitted on course at any time. Pacers must register at the designated check-in area, sign a waiver, pay a $15 fee, and wear an official "PACER" bib. Pacers must be 18+ (16-17 with parental consent), can only enter/exit at aid stations, and cannot provide physical assistance or carry the runner's supplies. Pacers may switch at any aid station but must check in with station personnel. Pacers are only eligible for water and emergency medical support at aid stations.

Family-Friendly 5K Option

Parents are welcome to run or walk the 5K course with their young children at no additional cost!

Organized in partnership with Healthy Kids Running Series Cedar Park. Proceeds support HKRS Cedar Park youth running programs.

Children MUST be registered to participate

Volunteer Opportunities

We Need Help With:

• Course Marshals

• Aid Station Support

• Registration/Packet Pickup Assistants

All Volunteers Receive:

• Race shirt

• Meal and snacks

• Community service hours

• Future race credit

Shifts Available:

• Morning: 7:00 AM - 1:00 PM

• Afternoon: 1:00 PM - 6:00 PM

Email: [email protected] to volunteer or click here

Ready for Your Colorado River Adventure?

Join us for this unique trail experience along the scenic banks of the Colorado River. Challenge your endurance and connect with nature!

REGISTER NOW!