Cussler would no doubt argue to the contrary, but the picture that emerges of him, from his books and from his biography, is of a man - and I mean this in the nicest possible way - who has never grown up.

It would be gratifying to criticise his work. Literature it ain't, but Cussler doesn't care. And why should he? He is in the business of ripping yarns; he writes them, people buy them. It is what we all wish we could do, which makes it all the more galling that he does it with such apparent ease.

There is little to say about Inca Gold that has not been said about Sahara. The action is relentless, the twisting and turning leaves the reader dizzy. You know Pitt will triumph, yet still you keep turning the pages.

Pitt is working off the coast of Peru as special projects director for the US National Underwater and Marine Agency. Experience, backed up by enviably thorough research, are the most potent weapons in Cussler's armoury.

Pitt intercepts a call for help from an archaeological expedition to a sacred well in the Andes. The expedition is trying to recover Inca treasure from its perilous depths - now two more divers have failed to surface.

This, as the plot suggests, is escapist entertainment with no pretensions. Pitt is a man of heroic dimensions and enviable tenacity, handling the improbable with nerves of steel and engaging in tremendous feats of derring-do.

It is a book in which characters never ''say''. Instead, they ''gasp'', they ''snap'' and they ''inquire breathlessly''.

Cussler's handicap is a failure to add anything to the thriller genre. One suspects he is not trying to and so it is difficult to argue that he should. But if the thriller is to rise above airport paperback status - as John le Carre has shown that it can - it needs more than Dirk Pitt, lost treasure and shadowy international organisations.