Head over here to get half off admission to the Biosphere 2. You’ll pay $20 for 2, $40 for 4, or $80 for 8 (usually $40, $80, and $160).

“The 75-minute under-the-glass guided walking tour takes guests from the visitor center into Biosphere 2′s three-acre complex. Guides lead tours through the ecosystems, research facilities, and multimedia exhibits housed within the historical enclosure.”

The discounted passes expire June 30th.