In Deep: Freediving, Renegade Science, and What the Ocean Tells Us About Ourselves, journalist Nestor, and a freediver himself, explores the practice of freediving and its application at the fringes of marine research.

Your subjects are freelance scientists who conduct marine research outside the established community. What is it about the ocean that attracts these outsiders with scientific inclinations?

The ocean has always attracted those living outside established, normal society. As far as the relationship with science, I just think that whenever you’re out in the water, you’re always curious to learn more. You’re always wondering, why are these dolphins coming up to me, what’s that weird clicking sound? I think it’s a curiosity that turns these guys into scientists, though none of them had really studied science.

And what drew you to such fringe scientists?

There’s amazing research going on [in larger institutions], but most of the research is done with robots. They’re looking at the ocean through a video stream. That’s not to dis the quality of their research—it’s just that I wanted to feel more of a connection. You can only learn so much about sperm whale behavior and communication from a boat or from a robot. You have to get in there and swim with them, and that’s what was so exciting about these freelance guys. That’s what they do.

In exploring the ocean for this book, what was the most humbling experience for you?

I think one of the starkest realizations was being down in a homemade submarine, 2,500 feet below the surface, and suddenly realizing the vast majority of the planet, and life on the planet, lives in complete blackness, very different from the world we experience here on the surface. That wasn’t so much a good epiphany as it was a depressing thought. It’s a very spooky, scary world down there. It made me grateful that I was lucky enough to be born up here and not down there.

You’ve written on altered states of consciousness. How does freediving compare as a method of expanded consciousness?

I meditate pretty regularly. I’m very interested in the science behind meditation, and freediving is the deepest meditation I can imagine, because when you dive, you’re demanded to go into a state of calm. You can’t freedive stressed out, you can’t freedive with your mind scattered. It’s very different from any other sport in that regard. It’s much closer to yoga than base jumping.

Any recommendations for people interested in freediving?

First thing I would do is take a course. There is so much safety that you should know about to freedive. Be prepared to slow yourself down. You’re not running a race. It’s a sport meditation. That’s something I think we need now more than ever. You don’t have access to any emails or texts when you’re in the water. It’s a great reprieve from all the hecticness of the modern world.