Waterworlds

And their discovery turns the established view of the origins of civilisation on its head.

These waterworlds have been discovered by Graham Hancock, whose previous books on lost civilisations earned him the description "the Indiana Jones of alternative archaeology".

Graham's latest quest starts at a crucial moment in pre-history: the end of the Ice Age, just before the supposed beginnings of civilisation.

Over a 10,000 year period, between 17,000 and 7,000 years ago, 25 million square kilometres of what were then the most habitable lands on earth where flooded by rising sea levels as the ice caps melted.

That's a landmass equivalent in size to the whole of South America and the United States added together. And it's an area on which no archaeology had ever been done.

This prompted Graham to ask a fundamental question. How can we be sure that archaeology has got the origins of civilisation right when so many of the areas where our ancestors lived have never been studied?

He decided to try to begin filling in this gulf in our knowledge. The results, detailed in his book Underworld: Flooded Kingdoms Of The Ice Age, the accompanying volume to the recent Channel 4 TV series, were astounding.

He discovered underwater monuments and temples in the Mediterranean, Caribbean and in the seas between China and Japan.

But the most astonishing find was off the coast of Gujarat in India: two huge ruined cities discovered 120ft under the sea.

They were flooded by rising sea levels almost 8,000 years ago, when no cities of this scale or sophistication are known to have existed anywhere on earth. And they must have been established long before that.

These cities had lain undisturbed until an inquiring mind combined with cutting edge marine archaeology techniques revealed them to the world again. And their existence rewrites human history.

It is a fantastic scoop. But Graham had to take big risks to get it.

He had to swim with sharks and other predators. ("Sharks don't eat divers", Graham insists. Well, not often.) He had to avoid fast-flowing undercurrents. But neither of these constituted the greatest hazard.

"The single greatest danger facing any diver isn't sea creatures. The greatest danger is surfacing and finding your boat gone," he said.

"This has happened to me several times. In Japan, the boat was so far away I only just saw it."

Despite such traumas, he intends to dive again, continuing his quest to find more underwater worlds. He is sure they are down there.

"I think what we have discovered is part of a clearly distributed coastal marine civilisation. There is more to be found."

Some archaeologists don't take too kindly to Graham's work. His previous books on what he says are earth's forgotten civilisations were best sellers - but rubbished by certain academics.

So he has been very careful to ensure that Underworld is "as scholarly as it can be".

"I have tried as far as possible to learn everything I can about the science that's involved in all these areas," says Graham.

"What's happened is my previous books have included quite small mistakes which have been seized on by my critics and expanded to completely write off all my work.

"I was determined not to allow that to happen again."

He understands why the knives are out for him. His theories about lost civilisations drive huge holes in archaeological orthodoxy.

Some specialists have seen their work of 40 years undermined by his new approach. They are bound to hit back. Graham is robust enough to defend himself. Too much effort is put into ensuring the evidence fits existing theories, he argues, "rather than looking for things that people might have missed.

"I do think there's a kind of in-built arrogance in archaeology, more than in almost any other discipline."

Graham has made it his life's mission to go looking for things others have missed. In his previous book and television series, Heaven's Mirror, he used a combination of astronomy and religion to argue for the existence of highly developed cultures that pre-dated the Egyptians.

And that was before Underworld took the story a lot deeper - literally.

Weighing in at 740 pages, the book cannot be described as lightweight. As well as a thorough yet very readable narrative and some awesome photographs by Graham's wife Santha Faiia, many maps and diagrams are included to back up the author's thesis.

Our knowledge of the two-thirds of the world covered by water is astonishingly poor; Graham said "we have a better map of the surface of Venus than of the sea bed". With Underworld, he is beginning to change that.

Underworld: Flooded Kingdoms Of The Ice Age by Graham Hancock is published by Michael Joseph, price £20

Updated: 10:11 Wednesday, March 13, 2002