As worthless as the title suggests, Andy Tennant's misguided romantic comedy sends its cardboard characters on a protracted treasure hunt in the clear blue waters of the Caribbean, with lack lustre comic interludes to stave off our boredom.

National Treasure and its hare-brained sequel attempted a similar melding of genres with entertaining results, but Fool's Gold isn't in the same league, diving to preposterous depths to convince us to care about the former husband and wife heroes and their motley crew of sidekicks.

Leading man Matthew McConaughey wastes no time in losing his shirt to flaunt his one redeeming feature - the washboard stomach - but his constant smug grin in the face of almost certain death soon grates.

There's no screen chemistry whatsoever with Kate Hudson, who jettisons her usual ditzy screen persona (adopted wholesale from her mother Goldie Hawn) to play the sole voice of reason in the midst of the on-screen madness.

Co-stars compete to see who can create the most unintentional comedy with their accent.

Ewen Bremner puts up a valiant fight with a comical Ukrainian twang while Donald Sutherland's strained, plummy British tones are as unconvincing as Ray Winstone's wandering American, which quickly vanishes whenever his salty seadog has to scream and shout.

By an outlandish twist of fate, treasure hunter Ben "Finn" Finnegan (McConaughey) discovers evidence of a legendary, 18th century sunken booty called The Queen's Dowry on the very day he is due to complete his divorce from long-suffering wife Tess (Hudson).

When she fails to be impressed by his claims to have unearthed the one priceless treasure that eluded them all these years, Finn blags his way on board the yacht Precious Gem owned by billionaire Nigel Honeycutt (Sutherland), where Tess works as a steward.

Nigel's airhead daughter Gemma (Dziena) is instantly smitten with Finn and his rip-roaring tales of hidden Spanish riches, and she joins the expedition to raise the shipwrecked Aurelia and its cargo.

However, archrival Moe Mitch (Winstone) is already in hot pursuit of the prize, financed by ruthless gangster Bigg Bunny (Hart) and his bumbling henchmen Curtis (Hooks) and Cordell (Warner).

Fool's Gold is all at sea from the opening frames, failing to remain afloat either as an action adventure or as a frothy comedy.

McConaughey and Hudson try to keep a straight face as they follow the trail of clues, from one uninspired set piece to the next, while looking like they would gladly be in anyone's arms rather than each other's.