If you’re going to title your film “The Odyssey,” you need to be pretty certain it’s got enough narrative heft and thrust to justify the Homeric allusion. Celebrity oceanographer Jacques Cousteau’s life was inarguably rich in accomplishments and teeming with anecdotes, but despite some lavish spectacle, Jérôme Salle’s watery biopic doesn’t make a case for it as the stuff of great cinema.

Spanning roughly 30 years, as it follows the Frenchman’s evolution from eccentrically ambitious naval officer to internationally revered explorer and ecologist, the film episodically ticks off the years without finding a galvanizing biographical arc in its subject’s professional or personal activities — and for much of its running time, appears torn between telling Cousteau’s story and that of his ill-fated son and collaborator Philippe. Handsomely lacquered production values and an under-exploited name cast — including Lambert Wilson as the red-beanied captain and Audrey Tautou as his long-suffering wife Simone — give “The Odyssey” some commercial ballast, particularly on home turf, but this San Sebastian curtain-closer won’t capture viewers’ imaginations as Cousteau’s own documentaries did.

The closing credits of “The Odyssey” begin with an unusual disclaimer, or perhaps simply a claimer: Citing the books on which Salle and co-writer Laurent Turner based their version of Cousteau’s life, including a 2012 memoir by his son Jean-Michel, it goes on to state the extensive research and interviewing work apparently undertaken by Salle himself in the scripting process. Presumably intended to safeguard the film against accusations of factual infidelity, it seems preemptively defensive: There’s not much in “The Odyssey’s” earnest account that seems too compelling to be true, even as it glosses over certain complexities in typically expository biopic fashion. Cousteau’s litany of extra-marital affairs, for example, is addressed in a single scene of confrontation between him and Simone; as a character portrait, the film may thus fend off potential accusations of hagiography, but unlike its deep-diving protagonist, it’s mostly content to float on the surface.

It is, at least, an attractive surface. A relative newcomer to features, cinematographer Matias Boucard lends a glinting National Geographic glaze to a dazzling array of global exploration locations — a number of them played by ever-versatile stands-ins Croatia and South Africa. (The latter served as the setting of Salle’s previous feature, the wobbly English-language cop thriller “Zulu” — on which “The Odyssey,” however uneven, represents a considerable improvement.)  Smooth, crystalline underwater lensing, meanwhile, appropriately showcases technical advances in the field that Cousteau himself pioneered. What he’d have made of the film’s elaborate digital interventions — notably in one vivid, nightmare-fueling swimming-with-sharks sequence — is another question.

In a move that has become all but de rigueur in prestige biopics these days, “The Odyssey” begins with a significant flash-forward, detailing the circumstances that caused Philippe Cousteau (played by the currently ubiquitous Pierre Niney) to crash his flying boat into a Portuguese river in 1979. It’s the first of several times Salle and Turner tease the possibility of framing Cousteau’s life through that of his son, though the film never fully commits to a perspective. Winding back 30 years, Cousteau’s formal departure from the French Navy and his first forays into oceanography are covered more or less through the eyes of 10-year-old Philippe and his older, less-favored brother Jean-Michel. Several key figures in Cousteau’s career are introduced in hazy, haphazard fashion, and even Simone (under-sketched throughout, though given occasional stabs of piquancy by Tautou) gets short shrift from the outset.

Old-fashioned montages and other time-marking devices — such as a long pan over Philippe’s conveniently postcarded locker at boarding school — fill in the essential facts of Cousteau’s rising star as an explorer and filmmaker. Matters gain some focus and tension when Cousteau is reunited with his grown, semi-estranged son, and they begin an on-off professional partnership, but neither man is written in especially penetrating or sympathetic fashion. Standard-issue daddy issues are the order of the day, while secondary narratives involving Cousteau’s draining U.S. television career, Philippe’s marriage to an American model — granted less screen time than certain sea lions — and their shift into environmental activism are dramatized in perfunctory bullet points.

An actor rarely inclined towards overstatement, Wilson (aided by some seamless ageing makeup) brings a sort of rakish gravitas even to Cousteau’s most child-like impulses, somehow maintaining his dignity when donning the signature Cousteau headgear (“It’s telegenic!”) that younger viewers are likelier to associate with Bill Murray’s Steve Zissou. Niney, for his part, plays both Philippe’s early callowness and gradually acquired idealism with equal brooding intensity; neither actor’s performance is quite the one to animate this largely Wikipedic enterprise.

But if its dry-land action remains, well, on the dry side, “The Odyssey” is — to crib a line from Sebastian the crab — better down where it’s wetter. Rote as biography, Salle’s film instead best honors its subject by inviting audiences to marvel at what lies underwater, whether it’s a seal lunging at the camera lens or, in one lyrical sequence, a majestic, storm-skinned whale drifting peacefully in the blue. The camera and digital effects teams have done their best to bring a sense of wonder to proceedings; trying a little too hard on that front, however, is the redoubtable composer Alexandre Desplat, whose ornate but frankly overbearing score leaves no emotional response to chance. Cousteau may have christened the sapphire depths “The Silent World” in his Oscar-winning documentary of that name, but Desplat’s relentlessly keening strings have other ideas entirely.

Film Review: ‘The Odyssey’

Reviewed at San Sebastian Film Festival (Official Selection, closer), Sept. 23, 2016. Running time: <strong>122 MIN. </strong>(Original title: "L'Odyssée")

  • Production: (France-Belgium) A Pan-Européenne, Curiosa Films, Moana Films, Wild Bunch, TF1 Films Production, Casa Prods., Versus Production, Voo, Be TV production. (International sales: Wild Bunch, Paris.) Produced by Nathalie Gastaldo, Philippe Godeau, Olivier Delbosc, Marc Missonnier.
  • Crew: Directed by Jérôme Salle. Screenplay, Salle, Laurent Turner, inspired by the books "My Father, the Captain: Life with Jacques Cousteau" by Jean-Michel Cousteau and "Capitaine de La Calypso" by Albert Falco and Yves Paccalet. Camera (color, widescreen), Matias Boucard; editor, Stan Collet.
  • With: Lambert Wilson, Pierre Niney, Audrey Tautou, Laurent Lucas, Benjamin Lavernhe, Richard Heneine, Chloe Hirschman, Roger van Hool, Thibault de Montalembert, Adam Neill, Olivier Galfione, Martin Loizillon, Ulysse Stein, Rafael De Ferran, Chloe Williams. (French, English dialogue)
  • Music By: