The flight time from Havana, Cuba to Key West, United States is roughly 40 minutes but, if you decided to swim instead, it’s a hell of a lot longer.  That was the self-imposed challenge of 64-year-old Diana Nyad who in 2013 became the first person (apparently) to swim across the Straits of Florida.  It was a 177km journey that look 53 hours and was completed with no sleep and without the aid of shark protective cage.  The achievement resulted in her becoming a quasi-celebrity which public speaking engagements, and a stint on the American TV series Dancing with the Stars.

It’s Diana’s 2015 memoir that serves as the source material for this biopic from Elizabeth Chai Vasarhelyi and Jimmy Chin, the married duo who won an Oscar five years ago for their edge-of-your-seat documentary Free Solo.  Nyad has the appearance of an uplifting, stereotypical “winning against all odds” tale and to an extent, that’s true.  You’ve got characters pointedly telling us about how you should never give up on your dreams despite how old you are.

To avoid this becoming too formulaic and predictable, screenwriter Julia Cox wisely adds other layers to the film.  Some of these are excellent.  The best is the interplay between Diana (Bening) and her loyal coach, Bonnie (Foster).  There’s a line from Bonnie which sums it up best – “do you have any idea how exhausting you are as a friend?”  It taps into the theme that in doing everything possible to achieve our own ambitions, we often forget the needs of those around us.

Both Annette Bening (American Beauty) and Jodie Foster (Silence of the Lambs) are terrific in illustrating the relationship between the two characters.  They’re not connected romantically… but it’s an incredibly close friendship where they often behave like a long-married couple.  When Diana stands up at a backyard BBQ and starts talking about herself too much, Bonnie quickly changes the topic in a way that minimises any hurt feelings.  She’s a skilled operator.

Other subplots aren’t handled as smoothly.  There’s a backstory involving child abuse which is fleetingly touched upon in quick flashbacks.  We don’t fully understand what happened to Diana nor how it has shaped the person she is today.  Qualms regarding her not-so-great father are also hinted at but never fleshed out.  One of the film’s least convincing elements is the way it shows Diana’s hallucinations (bright lights, Taj Mahals) while swimming.  I know it’s not easy trying to visualise what’s going through someone’s head but yeah, I wasn’t a fan of this approach.

With a supporting cast headlined by a scene-stealing Rhys Ifans (Notting Hill), Nyad is far from perfect (just like its protagonist) but worth a look-see.