Back in April, Leonardo DiCaprio (secretly) joined the TED Mission Blue expedition down in the Galapagos Islands to collaborate on initiatives related to ocean conservation. Joining him were celebs Edward Norton, Glenn Close, Damien Rice, Daryl Hannah and Chevy Chase — as well as about 100 esteemed guests and 25 inspiring speakers.

The six-day trip, produced in partnership with National Geographic, was the realized dream of oceanographer Sylvia Earle, who in 2009 won the distinguished TED Prize.

In a new interview with Rolling Stone magazine, DiCaprio says that while he was scuba diving near a pack of stingrays, he noticed something alarming about his gear.

“I was trying to get footage with a rinky-dink camera,” he told the magazine. “I looked down, because I was exerting myself a lot, and I think the tanks weren’t fastened properly, and I had, like 40 pounds of pressure.”

Admitting he was scared for his life, DiCaprio took a very deep breath and then swam over to the rest of the group to share oxygen. He added, “All you think about at that moment is, like, ‘Get me the hell out of this situation’.”

You can check out the full interview with Leo in the current issue of Rolling Stone on stands now.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

DiCaprio nearly drowned during TED eco-trip
Actor tells Rolling Stone that he feared for his life.