TMC Earth Day 5K at Biosphere 2
Walk · 5K
Apr 18, 2026 · Oracle, Arizona, US
Listed Jan 23, 2020
Run Vibes summary
AI-assistedAt a glance (AI-assisted text)
Celebrate Earth Day with a scenic 5K run/walk at Biosphere 2, supporting ocean reef research. Enjoy rolling desert views, post-race fun, and a free tour of the renowned facility.
The vibe (AI-assisted text)
This event offers a unique blend of environmental advocacy, scenic beauty, and relaxed fun, all set within the extraordinary Biosphere 2. It's designed for a broad audience, from casual walkers to runners looking for a pleasant challenge, united by a desire to celebrate Earth Day and support a meaningful cause. Expect a friendly, community-oriented atmosphere where participants can enjoy the unique surroundings and contribute to ocean research. The energy will be positive and inclusive, focusing on enjoyment and appreciation for nature.
Best for (AI-assisted text)
This event is ideal for runners and walkers who appreciate unique venues, love nature, and want to support an environmental cause. It's perfect for those seeking a fun, non-intimidating 5K experience with added educational and recreational value beyond the race itself.
Race day (AI-assisted text)
Race day at Biosphere 2 promises a relaxed and engaging experience. Packet pickup will likely be straightforward, leading into a start on the beautiful Great Lawn. The course itself, winding through Biosphere 2's backroads, will offer continuous desert and mountain views, making for a visually stimulating run or walk. After crossing the finish line, participants can look forward to a festive post-race atmosphere with music, food, and other fun activities. A major highlight is the included free entry to an informative tour of Biosphere 2, offering a unique 'backstage pass' to its diverse habitats.
Personality (AI-assisted text)
The TMC Earth Day 5K has an inviting and educational personality, blending the joy of running with a strong sense of purpose. It feels like a friendly gathering for environmentally conscious individuals and families, offering a chance to connect with nature and learn. The overall tone is one of appreciation, community, and lighthearted engagement, rather than intense competition.
Weather snapshot (AI-assisted text)
Taking place in Oracle, AZ in April, participants can generally expect warm, dry, and sunny conditions. While mornings might be pleasant, temperatures can rise significantly as the day progresses, so hydration and sun protection will be key. The desert climate typically means low humidity, but runners should prepare for potential heat.
Terrain & course feel (AI-assisted text)
The course is described as 'entirely on the grounds of the famed facility' and utilizes 'hidden Biosphere 2 backroads.' This suggests a mix of paved and possibly well-maintained gravel surfaces. It's a 'rolling 3.1 mile course,' so expect some gentle inclines and declines rather than a completely flat route, offering a varied but manageable challenge.
Signals we noticed (from listing text, AI-assisted)
- Earth Day theme mentioned
- 5k run and walk
- entirely on the grounds of the famed facility
- rolling 3.1 mile course
- perfect for racing and walking
- gorgeous desert and mountain views
- start and finish on the beautiful Great Lawn
- relax, listen to music, snag some food, and enjoy other fun activities
- free entry to the Biosphere 2 informative tour
- raising funds for the Ocean Reef research project
- Souvenir shirt to fir
This section is produced with AI from the listing we have on file—think of it as a quick orientation, not a rulebook. Organizers can update start times, courses, policies, and perks at any time, so when something really matters, please lean on their official race page for the latest. We don’t independently verify every detail against live organizer updates; we’re here to help you get a feel for the event and decide if you want to dig deeper.
Original listingFull description from sourceExpand the official listing text (unchanged)▾
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.
Clear your schedule and join us at the April 18th TMC Earth Day 5k, 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.
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!
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.
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Souvenir shirt to first 600 registrants
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Timed 5k with finisher's video
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Age group and overall awards courtesy of The Running Shop
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Free entry to the world-famous Biosphere 2
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Snacks and drinks
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Food trucks with yummy post-race food for purchase
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Children's activities
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.
Yes: you can pick up the number/shirt of other people
Yes: you can shop for cool goodies at The Running Shop.
Yes: It may be crowded, so please be nice to everyone
Yes: Be sure to take pins and pin your number on the front of your racing shirt.
Saturday, April 18 at Biosphere 2, 32540 S Biosphere Rd, Oracle, AZ 85739
Please consider carpooling. Please park in the main parking lot at the Biosphere 2. Please follow the directions of the Biosphere 2 staff on hand.
7:15-8:15 am Race day registration and packet pick up in the parking lot by the front entrance at the Biosphere 2. Pick up your race shirt and colorful race bib number.
8:30 am Start time for TMC Earth Day 5k Run/Walk
8:30 or so: Food trucks, with snacks and drinks available for purchase
9:45 am Free Kids Dash on the Great Lawn
10:00 am Awards, courtesy of the Running Shop. Remaining shirts available to late registrants, first-come, first-served.
10:15 Event wrap-up
Tour the Biosphere 2: All registrants can visit Biosphere2 on their own -- no need for a formal tour! All non-running guests can purchase Biosphere 2 admission for the discounted rate of $10 (before 8:30 am) and all children under 12 are free.
Post-race: If you can't make the race weekend activities, please note that any remaining shirts will be brought to the Running Shop and available for pickup between April 21 - May 15. To get the size you want, pick up your shirt in advance.
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! I’ve been fortunate to attend all the races you’ve had out there! Just the view and space is incredible and what a gift to be able to “struggle” up the hills while taking it all in! Thank you so much for all you and your staff/team do.
Nice words from 2024 runner Louise: Wow!! Are you guys efficient or what? Thanks so much for the quick turnaround with results and, again, for organizing and running a great event. The water stop was especially appreciated on a hot day. (And even if we were running short of time, the announcer was funny and added an enjoyable element to announcing the winners.)
Don't miss this chance to visit the earth's entire ecosystem under one roof while celebrating Earth Day.
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.
Do Good! This inaugural event raises funds for the world-renowned Biosphere 2's Ocean Reef Lab.
Terrain: mostly pavement, with a brief dirt section
Difficulty: hilly in sections
Weather: 50's - 70's
Differently Abled: Yes, be mindful of hills and dirt road
Pets Allowed: No
Want Training Advice? Contact RRCA-certified running coach Tia Accetta at tia@runtucson.net.
This event is a partnership between Run Tucson & the Biosphere 2, the University of Arizona
Questions? Contact Race Director Randy Accetta at randy@runtucson.net.
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