Underwater scenes

“Underwater there’s this whole system — I think it’s how we communicate with whales (laughs). We can actually hear voices underwater. I don’t know how, it’s crazy. I hear enough voices outside the water, I don’t need to hear it while I’m swimming.

There’s a lot of tests that you don’t expect to have to deal with. I had to hold my breath for a really long time. I always kind of prided myself with breath holding contests, but when there are elements involved like swimming through murky water…getting a certain piece of the vest snagged, very precise movements and struggling…there’s a lot more oxygen you use and it’s hard to hold your breath. Not to mention the acting too!”

Zac Efron, talking about underwater scenes in a featurette for Charlie St. Cloud.