The famous science fiction writer Sprague de Camp, the author of almost a hundred books, including popular science and history, talks about continents and peoples that long ago disappeared from the face of the earth, and perhaps never existed in reality. The author conveys legends that have acquired new details over the centuries, and cites the opinions of philosophers, writers, scientists about the likelihood of the existence of Atlantis, Lemuria, the continent of My and the possible connection of the ancient Egyptians and Mayans with the Atlanteans. An unusually fascinating book plunges us into the abyss of time to see what has disappeared in the depths of the sea...