Oceanographer Jacques Cousteau introduced millions to the wonders of the deep sea via his documentaries, books and conservationist efforts, a legacy his son and grandchildren have embraced with equal passion. For siblings Fabien and Celine Cousteau, who join their father in the latest installment of Jean-Michel Cousteau’s Ocean Adventures entitled Call of the Killer Whale, a documentary about orcas debuting on PBS Apr. 22 at 8 p.m., going into the family business was inevitable.

“The outdoors, animals, nature, exploration was just a part of our life,” says Celine. “It’s just what we do,” concurs Fabien, 41, who made his first dive at age four and went on his first expedition to Papua New Guinea three years later. “I’ve always been infused with the passion and there was never any question of it.”

It’s an enthusiasm inherited from Jacques, who began as a filmmaker and became interested in the ocean while in the Navy in the late 1930s, when few people had explored the undersea world. Then, encouraged to swim as rehab for a car accident injury, Jacques spent more time underwater, “and that captivated his curiosity and passion for the rest of his life. Unless you are passionate about what you do it makes you miserable,” says Fabien, whose venture into other fields only underlined his commitment.

He tried environmental products development and marketing, graphics design and sales management, “but they made me feel like I was slipping into a coma.” The pace was too slow and structure too restrictive for a peripatetic guy who’d found school similarly confining. “I’m the type of person who loves learning in the field.”

Celine, who studied psychology, got a masters degree in intercultural management, worked on sustainable projects in Costa Rica, and worked for a travel company, never lost her love of exploration that was rebooted when she documented the gray whale migration with her father’s team several years ago.

First enthralled by the photos and stories her mother, the expedition photographer, would share, she made her inaugural trip to the Amazon at age nine and it had “a huge impact” on her. Having joined Jean-Michel to film Return to the Amazon in 2006-2007 and visited several times since, she feels a strong tie to the region. “We grew up with the understanding that other people and other places were important in our lives regardless of how far away or remote because we were given the means to make all of those connections early on. I grew up understanding that I’m an integral part of the whole system,” Celine says. “My task is to reconnect people with the natural world to help them understand how they’re connected to that person in the Amazon.”

It’s a similarly vital connection between humans and the undersea world, Fabien points out. “Most people think of the ocean as an endless place that can’t be affected by what’s going on the surface when the opposite is true,” he says. “The ocean is 73% of our planet, and it’s been hugely affected by the activities of man. Ninety percent of pelagic species are gone. Fifty percent of all fish stocks in the ocean are gone from over fishing. It’s the careless lack of attention and thinking that the oceans are endless bounty and a garbage can for our activities. Look at the floating debris field in every one of our oceans. The Pacific garbage patch is the size of Canada and in some places it goes 90 feet deep.”

Fortunately, he tells MNN, the crisis is not too far along to fix. “These problems, whether they be global warming, garbage, over fishing, all stem from individuals and we’re the key to the solution. We just have to curtail our everyday bad habits.” When he switched to energy efficient appliances, CFL lighting, and began turning off electrics not in use, “over a year I ended up saving almost $1700. Take that up a notch for a family of four, and that’s money for a vacation.”

Celine points out that change “must happen at all levels,” including “supporting the organizations that do conservation work like the NRDC, who are fighting for this on a much bigger scale, and educating kids about protecting the environment.”

Fabien is writing an eco-aware children’s book trilogy “about the future of our planet, a fictional account based on reality,” and Celine plans to produce Into the World with Celine Cousteau, a series of short documentaries for TV and new media that will launch next year, probably with a piece set in Peru. “I will not be the star. My role is to help people discover and understand,” she says. “It’s all cultural, environmental context.”

While he won’t divulge the next expedition’s location, Fabien says it will be one of about four made each year that keep the Cousteaus busy year-round including pre-trip planning and post-production. “For every hour you see on TV we shoot between 160 and 200 hours of video. It’s a lot of editing,” he says.

Then there’s the creative challenge of balancing education and entertainment for an audience that’s increasingly cynical and bombarded with doomsday messages. The ideal documentary, he finds, addresses pertinent issues without lecturing “and empowers and impassions people rather than turns them off.”

The Call of the Killer Whale, he believes, does that by demonstrating how chemicals like PCB and mercury have contaminated the oceans and affect animals like orcas, and in turn, us. “That stuff is in our blood as well,” warns Fabien, who will conduct a live Web chat on Earth Day, Apr. 22 at 2 p.m. ET at www.pbs.org/engage.

He and Celine, four and a half years his junior, look forward to expeditions for the quality family time they afford, and hope to bring their own offspring along once they have them. While he’d support any career choice his kids make, “I would simply bring them on expeditions for life experience and open up their horizons and their eyes to different cultures and experiences both above and below water. My grandparents and parents never put any pressure on any of us to go into he family business. It was a natural call.

“Being born into this family is not just a passion but we carry a sense of responsibility,” Fabien says. It’s not a burden, but “more of an honor and a passion.”

Celine, who similarly would expose her children to experiences and let them decide for themselves, says she’ll teach them “to understand and respect other cultures, nature and their place in it, their connection to it and how to care for it.”

Following the example set by her mother and grandmother, who were vital behind-the-scenes participants in expeditions and proved to her that it’s possible to have both family and career, she’s “proud of being part of this family and also putting a woman’s face to the work we’ve done.”

Her first cousin, Alexandra, is doing that as well. She’s currently traveling around the world to promote her Expedition: Blue Planet water conservation initiative, a journey viewable online at www.dasani.com.

What would grandfather Jacques, who died at 87 in 1997, think of his grandchildren’s efforts?

“He’d be psyched,” Celine believes. “He set the foundation for us and for a lot of people and I think it would make him happy to see that we’re continuing his work.”