Transcript for In 'Secrets of the Whales,' an intimate look at the titans of the deep blue sea
I grew up in Massachusetts. And I can remember my parents taking me to the beaches of cape cod and Rhode Island, new Hampshire, as a little boy. And truly falling in love with the ocean. Part of my brain was stimulated with the idea of exploration. What was lying out beneath those waves? Reporter: Four decades. That's how long "National geographic" photographer Brian scary has been trying to answer the question, what lies beyond the waves? I've read you spend over 10,000 hours underwater, is that true? Yeah, not in a row. Accumulatively. That's more than a year of your life. Yeah. Reporter: 10,000 hours captured through the lens of his camera, a lifetime of learning about our ocean friends. From sharks to sea turtles to whatever this is. Try to get a little, even like just down here -- Reporter: We're not finding any of those today. Just a few ducks. Small potatoes for an ace photographer like Ryan. When a great photo comes down to gesture and grace -- Reporter: When he's not snapping pics of ducks with me, Brian is filming something a bit bigger. Much bigger. Because his latest project brings us face-to-face, up close, too close even, to the biggest, smartest animals in our blue seas. Premiering on Earth day, national geographic's new series on Disney plus, "Secrets of the whales," brings together more than three years of whale watching like you've never seen it before. Why whales? Whales are great ambassadors for the ocean. They're very much like humans. They have parenting techniques, they have preference for ethnic foods, they have singing competitions, they do all these really cool things. Reporter: Brian is front and center as one of the faces of the series, telling us the intimate story of these captivating creatures. But behind the scenes, he has some help from a team of absolute rock stars. Welcome. Welcome to our waters. Reporter: I know you know who that is. "Aliens." "Titanic." "Avatar." The man who journeyed to the bottom of the ocean. Yep, none other than the king of the blockbuster himself, James Cameron. James, you know, the ocean has been an inextricable part of your career for as long as I remember. When you started making films 40 years ago, did you ever think that your storytelling and your conservation work would be so intertwined? I mean, I think it has to be a goal. You have to make that happen. But it was also just a natural convergence. I literally took kind of eight years out of my life between "Titanic" and "Avatar" to go exploring, to just satisfy my own curiosity, my own desire to be in the ocean, to project myself physically into that world and bring backstories. It was exactly what I imagined it to be. It was big. It was scary. It was wondrous. It was alien. There's only one truly white whale. Reporter: Brian and James, sure, they've got good voices. Like a ghost. Reporter: But not good enough to narrate nature documentaries in a world where David attenborough still lives. And just as mysterious. Reporter: For that, they needed to call in the big guns. Beluga whales. Reporter: Hollywood royalty, legendary actor sigourney weaver. Your voice very much guides us throughout this whole series. What's it like, you know, being a voice for these animals that otherwise can't talk? The narration was so well written. Humpbacked whale clans have a culture all their own. I have to remind myself to keep narrating, because it's so mind-blowing, sometimes, what you're looking at. I came to feel so much respect and love for them. Almost as if you're a member of the family. I think that was my job is to sort of be a storyteller, as if I was kind of a liaison between the ocean and land. It was such a privilege for me. They seem so much like us. Yet we've only begun to reveal the secrets of the whales. Reporter: So much learned, but so much left to learn. Especially when scientifically speaking, we know more about the surface of Mars than we do about our own oceans, which makes a moment like this truly extraordinary. One that really struck me was the orca mother grieving for her baby. That occurred on Thanksgiving day. It was cold, snowy, gray day. Put on my wet suit. I was thinking about my family back home, celebrating, wishing I was there. But went out in the fjord and saw this family of orca swimming purposefully through the field. In the water I saw this very emotional scene where the mom was carrying the dead baby on the top of her head. And the rest of the family was almost in this funeral procession, for lack of a better analogy. So very, very disturbing. They have emotion. They have grief. They have joy. They have play. They have family bonds. So they're as complex in so many ways as we are. But they've learned to live in perfect balance with their world. Reporter: A perfect balance that from time to time they graciously and confusingly choose to share with us. Had this female orca swimming to me with a stingray hanging out of her mouth. Then she drops to the bottom looking at this thing, she comes back and she's faced off with me. There's me, there's the whale, there's the ray in between. And as if offering me food. Like, are you going to eat that? Amazing. You could never script that. Reporter: Sharing this world, saving these animals, will take time and resources. The more we learn about these whales, the more we learn about how to help them and our environment. Once you become one with them, and their priorities become yours, and you understand there's so much to empathize with, that now it becomes, well -- they're also in trouble. The more in love we are with these animals, the more we learn about them and respect them, the more we feel a sense of challenge that we have to do the changes necessary to our society and our civilization to allow - ourselves to imagine a future hundreds of years from now where we still get to share this planet with these amazing creatures. Reporter: This world, our world, does not survive without our oceans. Whether it's the middle of the arctic or this tiny slice of southern Maine. Not just on Earth day. But every day. It's up to us to protect it. Over 10,000 hours underwater. Do you feel like you're just scratching the surface? Absolutely. We're not apart from nature, we're not above it. We're actually intimately connected to it. And there are these other sophisticated societies in the sea that might change the way we do everything. Our thanks to ashan. You can catch full episodes of "Secrets of the whales" on Disney plus. Disney is the parent company of ABC news.
This transcript has been automatically generated and may not be 100% accurate.