Since James Cameron's "King of the world" Oscar splurge, it's customary - in the film hack habitat at least - to view the hirsute helmer with some disdain.

Those who peer down their proboscises at the director will find little in "Ghosts of the Abyss" to persuade them of his merits. Equally, his legion fans will no doubt enjoy the blend of spectacle and mawkishness he stirred to such (commercial) success in "Titanic".

Accompanied by Bill Paxton - who filled the role of expedition chief in the wraparound sections of the 1997 film - Cameron literally journeys to the bottom of the ocean for a non-fiction exploration of the infamous wrecked cruiseliner.

Using remote control robots, he views the inside of the ship, showing audiences places that - to adopt the hyperbolic tone of the film - no human eye has seen for nearly 100 years.

Wooooo.

Shot in 3D and showing in the giant IMAX theatres, "Ghosts of the Abyss" is nothing if not spectacular. As Paxton and Cameron crouch in their subs, 12500 metres down, it's easy to share their sense of awe at viewing this eerie, de facto crypt.

Once the initial wow-factor fades, though, a simple question floats to mind: why bother?

Presumably there is biological and historical import to visiting the sorry ship, but Cameron never explains it. Using snippets of "Titanic", reconstructed scenes and CGI, he skilfully provides context for the murky rooms he's exploring, but never gives one for the expedition itself.

It comes across as merely an expensive exercise in wish-fulfilment, with Paxton's voiceover providing an occassionally crass accompaniment. The inclusion of the crew's reaction to the events of 11th September 2001 is similarly misjudged.

It's valid to link the destruction of the Twin Towers with the similarly iconic Titanic, but given the picture's lack of purpose, these scenes add to the air of amateurism in a documentary which, despite all its interest, might as well be titled: "James Cameron: What I Did On My Holidays".