TMC Earth Day 5K at Biosphere 2

2027 Registration Open 2026 RACE DAY THANK YOU! Click here for the first post-race email to participants. Thank you for being part of this wonderful event! We hope you had a great time out there today! Results are at this race page or at www.roadrunnerracetiming.com . If you did not pick up your award, you can snag it at The Running Shop (3055 North Campbell) starting on Saturday afternoon at 3:0pm Remaining t-shirts are at The Running Shop (currently, sizes large and extra large), as are the handful of pre-purchased medals that did not get picked up. Please 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, so we do not have any more available to purchase. If you register after April 16th, please note that you cannot pick up a shirt before the race. If there are any remaining shirts after the pre-race packet pickup, 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 are on the various pages on this registration site, but you can also click here for the final pre-race email to all participants with race weekend details. 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 t