4000 Years Under the Sea by Philippe Diolé (Pan, 1957)

The fascinating pursuit of undersea archaeology has been much developed in recent years.  In this book Philippe Diolé , who wrote The Undersea Adventure, tells enthusiastically of 'free diving' experiences off the coasts of Southern France and North Africa.  He shows that the rewards are not won without a hard struggle.  A sunk ship laden with statues or wine-jars may be located; but it will be buried under a dozen feet of oozy mud.  A statue may be so encrusted with molluscs or overgrown with sea vegetation as to be unrecognisable.  To expose the walls of a Roman villa lying beneath the Mediterranean, divers worked four years, lifting first a top layer of sand, next a clay deposit thirty inches deep, and finally digging into pebbles and mud.  By linking the discoveries with history, M. Diolé gives fascinating information about seamanship, trade, wines and the spread of cultures in antiquity.