The Start: The event starts on the grass of the Great Lawn, crosses some gravel, then drops down a steep hill before heading up another hill that passes the Biosphere 2 complex.  For 2024, we've flattened this hill, with a flat and smooth section through Biosphere out buildings before a gradual climb to the top of the course. There are a few speedbumps on this opening hill, so please keep an eye out for varied terrain.

Mile One: After the first half-mile or so, you'll continue heading north through the Mesquite Forest.  This is a mostly flat section, then you'll take a sharp right turn and plunging downhill. Off to your left will be the snowcapped Catalinas as you head downhill, then you'll begin a gentle climb back up to the beautiful dirt road section, with the mountains to your left and the Biosphere 2 to your right.

Mile Two: The second mile will be a bit twisty as you go past the historic ranch house, then swing downhill past the stables and onto the flat-ish out-and-back.

Mile Three and the Finish: There will be about a 1/3 of a mile of gentle downhill to the turnaround, then you'll come back heading towards the Biosphere 2. The final stretch will head back up the hill to the finish line in the middle of the Great Lawn.

Chair Athletes: Chair athletes may find this a doable but challenging course, with a couple of steep hills and the dirt road. 

Accessibility: While the race course is accessible to all, please be mindful of hills and varied terrain. Much of the Biosphere 2 campus is wheelchair accessible, though certain areas of the property are not accessible due the steep terrain and the presence of stairs. The majority of the biomes, including the desert, savanna, ocean and rain forest, are all accessible by wheelchair or scooter.

Strollers: Strollers are allowed in the race, but please be mindful of the hills and ensure that you are tied to the stroller you're pushing. Please remember sun protection.

Headphones: Headphones are allowed, but we request that you do not wear headphones while participating in the event. Enjoy the camaraderies of your fellow athletes, enjoy the scenery, and keep an ear open for rattlesnakes, javelinas, and other participants.

Wildlife: This event takes place in a rural environment adjacent to wilderness, so you may encounter any number of wild animals, including but not limited to rattlesnakes and other snakes, javelina, cattle, deer, wild turkeys, horses bobcats, and more. Please do not try to touch the wildlife. Please do not wear headphones so that you can hear danger.

Heat and Altitude: The race starts at approximately 3820 feet, so be mindful that you're at a bit of elevation. It looks like race morning may be about 50 degrees at the start, climbing to the mid-70's. Stay hydrated, wear sunscreen and a hat.

Measurements: The route is garmin- and map-my-run correct but not a USATF certified course.

Wanna' know more about the location?  Check out this video from 2011, with scenes from the early construction in the mid-80's.

Discounted Visitor Pricing: All runners receive free entry to the Biosphere 2, while all all Earth Run spectators 13 years and older receive the reduced general admission fee of only $10 per person. Children 12 and under are free between the hours of 6am and 10am. Your admission not only gets you access to the grounds but is also good for the Biosphere 2 Experience. 

The Biosphere 2 Experience app helps guides you around and through Biosphere 2 and includes never before seen photos and videos that visualize the science and 30-year history. Through science stories and interviews you'll have the opportunity to learn more about our amazing, world-class research as you traverse a safe (socially distanced) one-way path around the exterior and through the human habitat and wilderness areas of Biosphere 2. Your admission fee helps to support Biosphere 2’s education and research initiatives.

Pets and Service Animals: While pets are not allowed inside Biosphere 2 or on the grounds, service animals that are trained to do a specific task are welcome. Please do not leave pets unattended in vehicles.

Please carpool. There will be parking in the Biosphere 2 parking lot, but it would help if participants carpooled to share the drive.