Sat, Apr 17, 2027

TMC Earth Day 5K at Biosphere 2

Oracle, AZ

Registration openAnnual since at least 2020

5K5K

About the TMC Earth Day 5K at Biosphere 2

The course runs entirely on private Biosphere 2 grounds, on roads and paths closed to the public. You start and finish on a grass lawn, then move through gravel, pavement, and a short dirt stretch. The route drops down a steep pitch, climbs back past the main complex, threads through a mesquite forest, and passes a historic ranch house. The mountains are visible for much of it.

Packet pickup happens the evening before at a running shop in Tucson, where you can also pick up bibs for others in your group. Carpooling to the Biosphere is encouraged; parking is in the main visitor lot. After the race, food trucks are set up near the finish along with snacks, drinks, and kids' activities on the lawn.

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Finish-Time Stats

Going by the 2026 results, this is a decent-sized field, and the spread of finish times is wide, so this is a mostly recreational race rather than one for club runners.

5K · 2026 results

686finishers

19:30winner

41:57median

1:38:10cutoff

Top 3: Nathan Highley (19:30) · Nigel Gruff (20:04) · Brendan Tinoco (20:10)

The TMC Earth Day 5K at Biosphere 2 has been held every year since at least 2020. That is as far back as RunSignup's records for this race go, so it may well be older.

Where Would You Finish?

Enter a finish time to see where it lands against the most recent 5K results.

Median

See how your time stacks up nationally →

How we calculate these stats: RunSesh calculates these figures from the most recent published results of past editions, sourced from RunSignup. We show aggregates only: field size, winning and median times, and the cutoff. We never publish individual finisher tables. Last updated Jul 27, 2026.

Distances & Start Times

5K4/17/2027 08:30$35

3.1 Miles4/17/2027 08:30$12

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Common Questions About the TMC Earth Day 5K at Biosphere 2

Will I finish last at the TMC Earth Day 5K at Biosphere 2?

Almost certainly not. Half the 5K field finished slower than 41:57, and the last recorded finisher came in around 1:38:10, so there is a long tail of runners behind the middle of the pack. Most fields are far slower than people expect.

Is the TMC Earth Day 5K at Biosphere 2 a good first 5K?

A field of 686 is big enough that you will have company at your pace without feeling lost in a crowd. There is no qualifying time, and the finish-time spread above shows how varied the field really is. If it is your first 5K, that spread matters more than the winner's time.

How competitive is the TMC Earth Day 5K at Biosphere 2?

The 5K winner ran 19:30 while the median finisher took 41:57. That spread points to a broad, mostly recreational field rather than a race dominated by club runners.