In “Blue Mind,” a marine biologist explores how being close to the ocean can affect the human brain. (Bigstock)

Wallace J. Nichols spent nearly two decades as a marine biologist studying Pacific Ocean sea turtles and working with fishermen in Baja California, Mexico, to protect the turtles from poachers. But in the past five years, he has turned a new page, delving into neuroscience, human behavior and what he calls the “blue mind.”

Nichols, who lives near Santa Cruz, Calif., has come to believe that the best way to protect the oceans and its denizens is to make people value the good feelings that arise from being around water. Since 2011, he has organized a yearly “Blue Mind” conference bringing together researchers studying the human brain and the marine world. His new book, “Blue Mind,” combines personal stories and research studies to describe the healing power of water. He recently spoke by telephone with The Post.

What is the “blue mind”?

It refers to a mildly meditative, relaxed state that we find ourselves in when we are in, on or under water. It’s something I’ve been experiencing and observing my whole life. As marine biologists, we don’t get a chance to talk about that feeling seriously and publicly. Yet it is the reason I became a marine biologist. At the same time, none of the books about water ever talked about the human brain. For several years, I tried to give this away as an idea. This was a pretty big left turn. I dove in and started putting on conferences and inviting the best neuroscientists and pairing them up with aquatic professionals and listening and collecting the conversations. There’s now a huge network of people over the past five years who seem interested in being connected and pushing the research forward and figuring out how to apply it in practical ways.

(Little, Brown and Company )

What’s the connection between human happiness and the ocean?

When we step away from our high-stressed lives and step into nature, we get a shift. Physiologically, our brains and bodies change. We relax, and the quality of our thought changes. A different brain network activates. That brain network is available for a completely different kind of quality of thought which is much more introspective and self-referential. Oftentimes it leads to feelings of connectedness and that can lead to innovative thoughts. Early humans seeking a place to call home and seeing a place overlooking the ocean or river realized that it makes them happy. They said, “This is good, this is right, this is safe and the place to survive and thrive.” For us today, it could be going to a swimming pool or a second-floor balcony on the ocean. If the water is blue and it’s not polluted, you are getting a signal that is probably present in most if not all mammals.

Nineteenth-century doctors used to prescribe a long ocean voyage or beach stay as a cure for many ills. Were they on to something?

Clearly, it worked for some people, and they continue to suggest that. Doctors still do that, and now we know the physiology of stress and that it is implicated in a variety of diseases. Often I will ask people to describe your healing place, [and they will say] it’s a place with water. They will say, “I’m sitting at the dock, or on the water.” That’s what people think of when they think of reducing stress. Go there literally or in their imagination. Sometimes imagining the place will help you more than going to the place itself.

Many of us can’t afford an ocean view. How can people experience the “blue mind” without buying a house on the water?

We forget that wherever we are, there is water all around. Be mindful of your water, pay attention to the way the water makes you feel in the shower. When you swim laps, if you pay attention when you touch the water and while you are swimming, it’s pretty interesting. Your brain goes into a different mode. My mom doesn’t go in the water. She had some experiences that scared her, and she doesn’t want to get water near her face. Finally I got her in the ocean last year with my daughters, and held her and she relaxed and enjoyed it. I had never seen her that relaxed in her entire life.

Given all the threats faced by the ocean, how is understanding the “blue mind” going to make a difference?

First of all, how much is an ocean worth or a river worth or nature worth? My experience and research suggest those are very important values and benefits and services. The cognitive and social capital of healthy waterways is enormous. People hold their most important ceremonies near water. They relax near water, they get creative near water. If that water is dead, you don’t have your ceremony next to it or on it. These are the things that make life worth living, but we don’t include them in our spreadsheets. We massively undervalue the oceans. I work with a group of veterans who use surfing and kayaking to help with PTSD. They now realize that healthy water is important to them. And they are now all ocean conservationists; they realize the ocean or river saved their lives and make sure it’s available to save their lives. Access to the “blue mind” means access to a waterway that isn’t polluted.

Niiler is a freelance science writer in Chevy Chase.