Biosphere 2
32540 S Biosphere Rd, Oracle, AZ
Oracle, AZ
A three-acre world under glass in the Arizona desert, complete with its own rainforest, ocean, and fog desert, built to see whether people could live sealed inside a tiny copy of planet Earth.
Rising out of the Sonoran Desert north of Tucson is one of the strangest and most ambitious structures ever built: a three-acre world sealed under glass and steel, containing its own rainforest, its own ocean with a coral reef, a mangrove swamp, a savanna, and a fog desert, all packed beneath soaring geometric domes. This is Biosphere 2, named for the idea that Earth itself is the original Biosphere 1, and it was built to answer a wild question. Could human beings survive inside a completely closed, self-sustaining copy of our planet?
In the early 1990s, eight people found out. They sealed themselves inside for two years, growing their own food and breathing air recycled by the plants around them, in an experiment that made headlines around the world. Today the facility is a working University of Arizona research lab studying how the real Earth works, and it opens its doors so visitors can walk through those sealed worlds themselves, from steamy rainforest to salt-sprayed shore, in a single afternoon.
What Guests Love
- Walking inside a sealed rainforest, ocean, and desert all under one glass roof
- The strange, beautiful glass-and-steel architecture in the middle of the desert
- The wild true story of eight people living sealed inside for two years
- Seeing real climate and Earth science being done today
Worth Knowing
- It is open to the public for tours most days; check hours and buy tickets before you go
- Tours involve walking and stairs through warm, humid biomes, so wear comfortable shoes and dress in layers
- It sits about 45 minutes north of Tucson near the town of Oracle, an easy half-day trip
- Summer afternoons are hot outside and muggy in the rainforest, so mornings are most comfortable
Details
Oracle, AZ
Learn about Biosphere 2
A miniature Earth under glass
Biosphere 2 was built between 1987 and 1991 as the largest closed ecological system ever created, an airtight structure enclosing more than three acres beneath a canopy of glass and white space-frame steel. Inside, engineers and scientists assembled miniature versions of Earth's major ecosystems: a lush tropical rainforest, a million-gallon ocean with a living coral reef, a mangrove wetland, a grassland savanna, and a coastal fog desert, along with farm plots and living quarters for a human crew.
The goal was to see whether such a system could sustain itself, and its people, entirely on recycled air, water, and food, the kind of closed world that might one day be needed to live on the Moon or Mars. Walking through it today, visitors pass in minutes from dripping jungle to open desert, all of it thriving under the same enormous glass roof, a genuinely surreal experience in the middle of Arizona.
The two-year experiment
In September 1991, eight people, called biospherians, walked inside Biosphere 2 and the doors were sealed behind them. For two years they lived entirely within the structure, growing and cooking their own food, tending the ecosystems, and breathing air cleaned by the plants around them, cut off from the outside world in one of the most famous science experiments of its era.
It did not go smoothly. Oxygen levels fell and had to be topped up, crops struggled, some animals died off, and the crew grew hungry and divided, all of it followed avidly by the press. Yet the mission also produced a mountain of real data and an unforgettable lesson in just how complicated it is to keep even a tiny world in balance. The story of those two sealed years is the heart of every tour, equal parts science, adventure, and human drama.
A living laboratory today
After its original missions, Biosphere 2 found a lasting purpose as a research facility, and it is now operated by the University of Arizona. Scientists use its enclosed environments to run experiments that would be impossible in the open, from studying how rainforests respond to drought to a vast hillside of engineered soil, the Landscape Evolution Observatory, where researchers watch water and life shape bare ground in real time.
That makes a visit a rare chance to see big Earth science actually happening. Tours wind through the biomes and behind the scenes into the technical underworld of pipes and machinery that keeps it all alive, and the guides connect the wild 1990s experiment to the urgent questions about climate and water that the facility helps answer now. It is part time capsule, part working lab, and wholly unlike anywhere else.
Closest Boutels
The closest Boutel™ stays, so you can turn this stop into an overnight. Each is an independently owned, editorially selected place to stay.
Things to Do Near Oracle
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Catalina State Park
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Mount Lemmon Scenic Byway
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Saguaro National Park
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