Digital effects have come a long way since Yann Martel’s adored novel Life of Pi was first published in 2001, without which director Ang Lee’s efforts to bring this supposedly unfilmable book to the big screen would have been scattered on the rocks.

It’s an achievement in itself by David Magee to turn Martel’s prose into a screenplay and Lee, in his first film since the passable Taking Woodstock (2009) deserves a lot of credit for realising on screen the many wonders Pi (Suraj Sharma) witnesses during his epic journey.

Certainly in the past, many effects-laden films have sacrificed the things which should come first – a good script and good performances – for the sake of an attention-grabbing shot or action sequence. Lee for his part seems to have learned a thing or two about finding the right balance since falling into that trap with the disengaging Hulk in 2003.

The biggest challenge facing Lee was to give us a convincing Richard Parker, a Bengal tiger that, like the titular Pi, finds itself on a Japanese cargo ship on its way across the Pacific to start a new life in Canada.

Except neither the teenage Pi nor Richard Parker have any say in this. Piscine Militor Patel, or Pi as he prefers to be known after being given the unwanted nickname ‘Pissing’ Patel at school is happy living in the zoo his family owns in Pondicherry, India. Seeking a new life for them all, his father closes the zoo and books passage on a ship for both his family and animals, which will be sold abroad.

In a scene both vivid and distressing, the ship sinks after getting caught in a terrible storm. Pi is the only human to make it off the vessel alive, but finds he isn’t alone in the small lifeboat; he’s joined on board by a zebra, a hyena, an orangutan – and Richard Parker.

The storm is a stark reminder for the stricken Pi of nature at its most untamed and recalls an earlier scene when a younger Pi tries to feed Richard Parker and is chided by his father, who shows him that “a tiger is not your friend” by making him watch it kill a goat. Stuck in the lifeboat, he is given a further unpleasant reminder when he witnesses the law of the wild inevitably taking effect. After watching this, the knock-about opening credits which playfully show the zoo animals going about their daily business take on a rather different light.

The teenager names the boat ‘Pi’s Ark’, one of many religious and spiritual references in the film. Pi is shown as a young boy embracing Christianity, Hinduism and Islam, much to the annoyance of his scientifically-minded father, and the extraordinary quest on which he embarks with Richard Parker aboard the boat is as much about spiritual self-discovery as it is about survival.

It’s when the boat is adrift at sea that the digital light show really takes over. In spite of falling back on the requisite ‘poke things at the screen’ trick to justify the use of 3D, Lee and his digital effects team conjure up myriad striking images. These range from the beautiful (the boat sat on perfectly still, glassy water) to the wonderfully bizarre (the moment hundreds of flying fish thunder by the boat is one of the film’s most memorable scenes).

The encounters Pi has are both frightening and fantastical – a belly flop from the biggest whale you’ve ever seen and the weirdest island (shaped like a woman) this side of Lost. They also speak to a key theme of Life of Pi, the power of faith. The adult Pi (played by Irrfan Khan) relates his story to a writer (Rafe Spall) devoid of ideas for a new book and bestows it on him to do with it as he pleases (“the story’s yours now”).

Setting aside all the remarkable computer work, Lee’s film works best as a simple buddy story between a teenager and a tiger. Although no masterpiece, Life of Pi is far from being a shipwreck and for an ‘unfilmable’ tale that’s an achievement in itself.