GROWING up is hard to do, but it doesn't get any easier when you're older, according to this perfectly low-key adaptation of Joe Dunthorne's raved-about novel.

A coming-of-age story set against a backdrop of kitchen sink drama, schoolyard angst and dry humour, it follows teenager Oliver (Craig Roberts) on his quest to win the affections of classmate Jordana (Yasmin Paige) - first by posing as a bully, then by helping her get back at her ex-boyfriend.

But as Oliver wins her heart, he finds he must strike a balance between being the best boyfriend, ensuring he doesn't get his heart broken, and saving his parents' marriage.

The themes are many and varied and universal - love, heartbreak, mortality, depression, youth, bullying, sex, infidelity, family and the mistakes of the past - and its title comes from its many allusions to water as a metaphor for depression, and its suggestion that ultimately we need someone with us in the water to help keep us afloat.

Richard Ayoade (best known for his role as Maurice Moss in The IT Crowd) defuses the potential melodrama but never loses the heart by pushing some big moments off the screen or into the background and maintaining the focus on Oliver, his reactions and the fallout.

While the film moves along quietly and unhurriedly, it rarely drags, with Ayoade spicing the potentially heavy story with enough moments of hilarious awkwardness and humourous absurdity.

He also embraces his minimal budget to wonderful effect, managing some spellbinding sequences in spite of the lo-fi qualities, such as some pretty scenes involving two teens with flares and fireworks, an impressively faked freeze frame sequence as a girl falls into a pond, and a clever visual effect that turns Oliver's bedroom into an ocean.

Roberts is outstanding as Oliver, underappreciated Aussie actor Noah Taylor adds droll humour and illicits sympathy as Oliver's depressed dad, and Considine is laughably revolting in the small but pivotal role of Graham.

A low-key gem, Submarine has a lot to say and manages to say it intelligently, quietly and with a wry smile.