James Cameron will literally not let it lie - the wreck of the Titanic, that is.

Not content with helming the £1.2bn-grossing blockbuster about the doomed luxury liner, he wants the real thing ...on the seabed of the Atlantic, 2.5 miles down.

With a team of marine experts and historians, plus his old mucker Bill Paxton, he set off for the wreck of the White Star Line flagship.

Using 3D camera technology developed specifically for the job, he filmed everything from a bowler hat casually left on a cabinet to the vast Sphinx-like engines.

For the early part of the movie there's a lot of gawping at charts, loading cameras and stressing the technological marvel this mission is.

But once we're suspended above the enormous hulk, the grandeur of the spectacle takes over, relegating the submarine photo skills to the sidelines.

Developed specially for Imax cinemas, the vision of the decaying ship, its state rooms and first-class cabins lit by a vast suspended 'chandelier', are simply staggering.

Even so, there's a faint feeling that Cameron is playing technological hopscotch on the watery graves of the 1,500 who perished.

He makes amends for this macabre element by populating the crumbling decks with spectral crew and passengers in a series of touching vignettes.

Then he goes and spoils it all by introducing a distasteful 'sub-plot' when one of his ROVs (Remotely Operated Vehicles) gets trapped by a fibre optic cord.

You don't need to introduce artificial drama into a documentary, particularly one dealing with the legendary events of April 14, 1912.

Cameron insists the ROVs (nicknamed Jake and Elwood) were like members of the crew, but presumably that didn't mean they joined him for cocktails at LA's Sky Bar.

The reason for seeing this is not the hardware on show or the faux attempts to provide tension, but the chance to explore the wreck in 3D from the safety of your seat.

Cameron's main achievement is preserving footage of the liner for posterity - in less than a century, steel-devouring 'rusticles' will have returned it to nature.

Tim Evans