Beneath the waters of Abukir Bay, at the edge of the Nile Delta, lie the submerged remains of the ancient Egyptian cities Canopus and Thonis-Heracleion, which sank over 1,000 years ago but were dramatically rediscovered in the 20th century and brought to the surface by marine archaeologists in the 1990s. These pioneering underwater excavations continue today, and have yielded a wealth of ancient artefacts, to be exhibited in Britain for the first...