Until his death in 1997, explorer, filmmaker, and adventurer Jacques-Yves Cousteau was one of the 20th century’s most renowned environmental voices, attracting audiences around the world with his films that revealed the underwater secrets of the sea. But who was this tall, lanky Frenchman? How did he become that Cousteau?

To create this immersive visual portrait, two-time Oscar nominee Liz Garbus (What Happened, Miss Simone?) drew on almost 550 hours of footage, taken from Cousteau’s own, rarely seen films as well as from the Cousteau Society’s archives. Rather than rely on the traditional talking-head interview format, the director incorporated voice-overs from Cousteau’s audio journals and recorded conversations with colleagues, crew members, and friends, as well as excerpts from his letters and other texts, read by French actor Vincent Cassel. Kudos to editor Pax Wassermann for integrating this raw material so seamlessly into a cohesive, entertaining whole.

As the documentary reveals, curiosity was the driving force that shaped Cousteau’s professional and personal life. “Every explorer is driven by curiosity,” he said. “We must go and see for ourselves.” This inquisitiveness was first stirred when his friends Philippe Tailliez and Frédéric Dumas introduced Cousteau to snorkeling as a way to recuperate from a debilitating car accident that had derailed the young naval officer’s career as a pilot.

An avid filmmaker since the age of 13, Cousteau captured the trio’s 1930s aquatic adventures off the Riviera coast near Toulon in stunningly crisp black-and-white images. Sometimes joining the “Three Diving Musketeers” (as the local press called them) on the beach was Cousteau’s new bride, the stunning but camera-shy Simone Melchior. Coming from a naval family, she was as enamored of the sea as her husband, describing herself as having “saltwater in my veins.”

But Cousteau had an urge to go deeper and further. “I became an inventor by necessity,” he recalled. Working with an engineer, he developed the Aqua-Lung diving apparatus, the predecessor to modern scuba gear. The device revolutionized diving and made it possible for Cousteau and his team to salvage scuttled and torpedoed ships during World War II. Eerie, ghostly footage shows Cousteau’s divers recovering the corpse of a downed pilot, his parachute floating like a shroud.

In 1951 came the turning point in Cousteau’s life when he set sail for the Red Sea on board a converted minesweeper named Calypso, accompanied by a ragtag crew of so-called “dropouts.” In those early days, as seen here, the red-capped sailors were rather cavalier in their explorations of the natural world, catching rides with whales and doing handstands on the backs of tortoises. Also surprising is how Cousteau funded these initial voyages by working for oil companies, a choice he later regretted.

Although this film is co-produced by Cousteau’s widow and their two children, Garbus doesn’t shy away from the messier aspects of Cousteau’s personal life. “To be an explorer,” said elder son Jean-Michel, “you have to agree to have a sketchy family life.” Sent to boarding schools, Cousteau’s two sons spent holidays on the Calypso where Cousteau favored the more adventurous Philippe.

Garbus also gingerly probes Cousteau’s long-time affair with a much younger woman that produced two children. A striking shot of Simone Cousteau with her back to the camera gives the impression that she too might have known about her husband’s secret family. Six months after Simone’s death from cancer in 1990, the 81-year-old Cousteau married Francine Triplet, who now heads the Cousteau Society.

The director glosses over Cousteau’s World War II years, focusing on his diving and underwater photography experiments to the exclusion of his French Resistance exploits. Also absent is Cousteau’s tense relations with Jean-Michel, which included a lawsuit over the use of the Cousteau name.

Still, there’s plenty here to send Cousteau aficionados and newbies back to his glorious filmed adventures. The whimsical score by Danny Bensi and Saunder Jurriaans and the charming animated closing credits may also inspire viewers to watch Wes Anderson’s homage to the explorer, The Life Aquatic with Steve Zissou.