In their Oscar-winning 2018 film Free Solo, the filmmakers Jimmy Chin and Elizabeth Chai Vasarhelyi documented a man seemingly addicted to risk. Their subject was free climber Alex Honnold, who scales cliff faces without the use of safety ropes. The film asked probing questions about what could possibly drive a person to do this, while also standing in awe of his daring. It’s a fascinating film, cautionary and laudatory. 

It makes sense, then, that Chin and Vasarhelyi would choose Diana Nyad as the subject of their first narrative feature. Nyad is a marathon swimmer who, in 2013, after several failed attempts, swam 110 miles from Cuba to Key West at the age of 64. While still not officially certified as an unassisted swim (for various nettlesome technical reasons), Nyad’s was a boggling feat. She traversed shark- and jellyfish-infested waters for 53 hours, finally realizing a dream she’d held for 35 years. 

But why did she have this dream at all? Who would want to push their body to such extremes, jellyfish stings (from which Nyad suffered mightily) or not? Nyad only offers glancing answers to those questions. There is abstract reference to her father, who instilled in her a mandate to succeed. There are hazy flashbacks to a sexual trauma visited upon a young Nyad at the hands of a swimming coach. But for the most part, the film accepts Nyad’s near-suicidal conviction as a force without context. She just wants to do the thing, and that is reason enough.

Chin and Vasarhelyi have an athlete’s understanding of their subject, an appreciation of pure determination that may seem pretty alien to, say, a film critic who spends his days sitting passively in the dark. They make a persuasive case for the Nyad machine, though, staging her swims with frightening vigor. What a miserable struggle: thrashing against ocean currents, beset by wildlife, gasping for air. This is the visceral realm in which these filmmakers are perhaps most comfortable—they are keen studiers of stress and perseverance. Justice is done to the might of Nyad’s body and spirit, even if her character is only drawn in faint outline.

Nyad is played by Annette Bening, who trained for a year to ready herself for the physical demands of the role. It’s quite a testament to actorly commitment: This movie can’t have been fun to film, at least not for the person playing the woman who spends so much time working her way through the open ocean. Bening embodies both the grace and the unbearable strain of Nyad’s effort, its grandeur and its ugliness. 

She’s a pleasure in the film’s drier scenes too. Bening plays Nyad as a bit of a kook—because, obviously, anyone who would choose to swim for 53 hours straight has to be at least a little weird. Brash and self-involved, Nyad is not easy to love. But Bening thoughtfully maps the character’s insecurity, the loneliness of her tunnel-visioned pursuit. She urges an empathy for Nyad’s intense desire; who among us hasn’t wanted, fiercely, for some crazy thing to happen?

Bening has terrific support from Jodie Foster, an actor of exceeding appeal who does not work near often enough these days. (Not enough from the audience’s perspective, at least; I trust that she’s happy with her work-life balance as it is.) As Bonnie Stoll, Nyad’s best friend and eventual coach, Foster glows with affable charm. Chin and Vasarhelyi, working with Julia Cox’s script, also make room for Bonnie to assert herself, her own needs, devoted as she is to Nyad’s solitary mission—though, I suppose it’s not really that solitary. Nyad had some 40 people on several boats following her as she cut her way across the sea.

Vivid and bracing as the film’s swimming scenes are, Nyad crackles most when Nyad and Bonnie are grooving together on land. Bening and Foster have an inviting rapport, credibly playing old pals (and onetime lovers) who are in it for the long haul. It’s a thrill to see a movie that puts two lesbian friends, both in their older years, at the center of the story. Nyad is unfussy and matter-of-fact in its queerness, a rarity in the sports genre—or, really, any genre. 

While Bening is the centerpiece, Foster practically boats off with the movie. That’s because we spend so much engaging time with her, as Bonnie frets over and encourages Nyad, who is lost and distant in her mad charge toward greatness. Bonnie is our proxy, and Foster’s winsome performance sways us to her side. But Bening registers potently too. Nyad affords two great actresses in their 60s the opportunity to wrestle their way toward victory. That’s a triumph in its own right, no actual jellyfish required.