TMC Earth Day 5K at Biosphere 2

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32540 S. Biosphere Road, Oracle AZ

Saturday, April 18th, 2026

🌍 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.

🏞️ Event Details

Date: April 18, 2026
Location: 32540 S. Biosphere Road, Oracle, AZ
Course: A rolling 3.1 mile course with gorgeous desert and mountain views
Start/Finish: The race will begin and end 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, so make sure to stick around to socialize and have some fun. 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, a wild world of wetlands, rainforests, grasslands, fog deserts, and the big blue ocean. It's like a backstage pass to nature's superstar habitats!

🌊 Fundraising Goal

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.

👕 Runner Benefits

Souvenir shirt: to the first 600 registrants
Timed 5k: with 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 to the first 600 registered, sizing and style on a first-come, first-served basis.

Saturday, April 18 at Biosphere 2:
7:15-8:15 am Race day registration and packet pick up. Please carpool and follow staff directions.

🥇 Race Day Schedule

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 and remaining shirts available
10:15 am: Event wrap-up and free tour of Biosphere 2

❤️ Community Feedback

Nice words from 2024 runner Dale: It’s important to me to thank the people who help make Tucson the awesome community it is! Saturday’s Earth Day was fabulous!

Nice words from 2024 runner Louise: Wow!! Are you guys efficient or what? Thanks so much for the quick turnaround with results!

👶 Family Friendly

Bring the Kids! Strollers are allowed at this child-friendly event, with a free Kid's Dash & Kid's Zone. Special $5 price for children 14-and-under: includes race number, timing, and entry to Biosphere 2, but no t-shirt.