Between 17,000 years ago and 7000 years ago, at the end of the last Ice Age, terrible things happened to the world our ancestors lived in. Great ice caps over northern Europe and north America melted down, huge floods ripped across the earth, sea-level rose by more than 100 metres, and about 25 million square kilometres of formerly habitable lands were swallowed up by the waves.
Marine archaeology has been possible as a scholarly discipline for about 50 years - since the introduction of scuba. In that time, according to Nick Flemming, the doyen of British marine archaeology, only 500 submerged sites have been found worldwide containing the remains of any form of man-made structure or of lithic artifacts. Of these sites only 100 - that's 100 in the whole world! - are more than 3000 years old.
This is not because of a shortage of potential sites. It is at least partly because a large share of the limited funds available for marine archaeology goes into the discovery and excavation of shipwrecks. This leaves a shortage of diving archaeologists interested in underwater structures and a shortage of money to pay for the extremely expensive business of searching - possibly fruitlessly - for very ancient, eroded, silt-covered ruins at great depths under water. Moreover, with the recent exception of Bob Ballard's survey of the Black Sea for the National Geographic Society, marine archaeology has simply not concerned itself with the possibility that the post-glacial floods might in any way be connected to the problem of the rise of civilizations.