Avatar: The Way of Water review – a soggy, twee, trillion-dollar screensaver

Drenching us with a disappointment that can hardly be admitted out loud, James Cameron’s soggy new digitised film has beached like a massive, pointless whale. The story, which might fill a 30-minute cartoon, is stretched as if by some AI program into a three-hour movie of epic tweeness.

The first Avatar was a pioneering 3D sci-fi spectacular which Cameron delivered in 2009. Now, after 13 years of unimaginably expensive pixel-crunching, the aquatic followup has arrived, with a third and a fourth on the way. This one is available in 3D and 2D, and so at any rate keeping loyal to that three-dimensional vision that Cameron almost single-handedly revived but which the rest of the industry has quietly forgotten about. Yet the whole idea of the “avatar” from the first movie – the artificially created body that can be remotely piloted into an unknown world and which crucially formed a dramatic part of the audience’s 3D experience – has been left behind.

The effects now, technically impressive as they are, amount to high frame-rate motion smoothness which is soulless and inert, creating not so much an uncanny valley but an uncanny Mariana Trench down in the depths. Cameron’s undersea world is like a trillion-dollar screensaver. Where is the oceanic passion and jeopardy of great Cameron movies such as Titanic or The Abyss?

The situation is that ex-human Jake Sully (Sam Worthington) is committed to the Na’vi body he assumed when insinuating himself among the blue-bodied, pointy-eared tribe as part of the “avatar” strategy in the first film, before falling in love with dynamic warrior Neytiri (Zoe Saldaña) and siding with her people against the humans who would exploit the Na’vi’s mineral resources. Now, some years later, Sully and Neytiri are living happily with their children and their stepdaughter Kiri – whose connection with the original film soon becomes apparent – and also a semi-feral human kid called Spider.

But just when they thought they were happy, the “sky people” of planet Earth reappear and there is an admittedly ingenious twist concerning the gung-ho marine colonel Miles Quaritch, memorably played by Stephen Lang. Sully’s family have to leave their rainforest habitat and hide away among the far-off Metkayina, an amphibious reef people led by Ronal (Kate Winslet) and Tonowari (Cliff Curtis). There they must learn the mystical Metkayina art of existing for long periods underwater. Sully’s children and Tonowari’s children, at first spiky and rivalrous, become as close as cousins. But this new Eden can’t last forever either.

The submarine world of this film is, in its way, its chief character and its whole point. The move from land- to sea-based existence is the way a new film was created. But the sea world is imagined with a lot of cliche. Frankly, there isn’t a single interesting visual image and the whole thing has the non-briny smell of a MacBook Pro. Finding Nemo was more vivid.

And what do we find aside from the high-tech visual superstructure? The floatingly bland plot is like a children’s story without the humour; a YA story without the emotional wound; an action thriller without the hard edge of real excitement.

• Avatar: The Way of Water is released on 15 December in Australia and 16 December in the US and UK.