TMC Earth Day 5K at Biosphere 2

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32540 S. Biosphere Road, Oracle AZ

Saturday, April 17th, 2027

🌍 2027 Registration Open

Join us as we prepare for the TMC Earth Day 5K at Biosphere 2 on April 17, 2027. The registration for this exciting event is now open!

🎉 2026 Race Day Thank You!

Thank you for being part of this wonderful event! We hope you had a great time out there today!

Results: Check results at this race page or at www.roadrunnerracetiming.com.
Awards Pickup: You can snag your award at The Running Shop (3055 North Campbell) starting on Saturday afternoon at 3:00 PM.
T-shirts: Remaining t-shirts are available at The Running Shop, sizes large and extra large, as are pre-purchased medals. Bring proof of purchase if you want to snag your medal.

⚠️ April 16 Update

We've reached our cap and have sold out of the souvenir medals. If you register after April 16th, please note that you cannot pick up a shirt before the race. Any leftover shirts will only be available after the race, on a first-come, first-served basis at the Run Tucson tent.

🔍 April 14 Update

All race details can be found on various pages of the registration site. You can also click here for the final pre-race email to participants with race weekend details.

🏃 Celebrate Earth Day

Looking for a way to celebrate Earth Day? Join us at Biosphere 2 for a 5k run and walk, entirely on the grounds of the famed facility. Whether you're a seasoned athlete or just looking for a fun way to get some exercise, you’re sure to enjoy yourself at the world-famous Biosphere 2.

🏞️ Course Details

Clear your schedule and join us on April 18th, where you can walk or run the hidden Biosphere 2 backroads, nestled at the base of the majestic Catalina Mountains, north of Tucson. The rolling 3.1 mile course is perfect for racing and walking, with gorgeous desert and mountain views and a start and finish on the beautiful Great Lawn.

🎶 Post-Race Activities

After the 5k, you can relax, listen to music, snag some food, and enjoy other fun activities. Make sure to stick around to socialize and have some fun.

💲 Pricing

Pricing is $40 for the 5k, which includes race entry, a souvenir shirt, and free Biosphere 2 entry. A special price of $10 is available for children 14-and-under, which includes the 5k race and entry to Biosphere 2, but no souvenir shirt.

🌳 Ongoing Tours of Biosphere 2

Explore a 3.14-acre living laboratory where cutting-edge research unfolds across diverse ecosystems—including the Landscape Evolution Observatory. All registrants receive free entry to the Biosphere 2 informative tour of the renowned research facility, with an exclusive peek into the inner workings of the Biosphere 2.

🌊 Fundraising for Ocean Reef Lab

The TMC Earth Day 5k is raising funds for the Ocean Reef research project, learning how to grow ocean reefs in a changing climate. See details and donate here.

🎁 What You Get

Souvenir Shirt: Provided to the first 750 registrants.
Timed 5k: Includes finisher's video.
Awards: Age group and overall awards courtesy of The Running Shop.
Free Entry: To the world-famous Biosphere 2.

📅 Schedule

Thursday, April 16

4:00 - 6:00 PM Packet pickup and in-person registration at The Running Shop, 3055 North Campbell, Tucson.

T-shirts are given to the first 750 registrants, with sizing and style on a first-come, first-served basis. Please bring pins to attach your race number.

Saturday, April 18

Location: Biosphere 2, 32540 S Biosphere Rd, Oracle, AZ 85739. Carpool if possible and park in the main parking lot.

7:15-8:15 AM: Race day registration and packet pickup.

8:30 AM: Start time for TMC Earth Day 5k Run/Walk.
9:45 AM: Free Kids Dash on the Great Lawn.
10:00 AM: Awards, courtesy of The Running Shop.

👶 Family Friendly

Bring the Kids! Special $10 price for children 14-and-under in the 5k includes race number, timing, and entry to Biosphere 2, but no t-shirt. Running strollers are welcome, but be mindful of the hills!