Platonis is a man-made island in the middle of the Atlantic Ocean on Earth. It is fifty miles across and singularly inhospitable. In the 2350s, this island was part of Starfleet Academy's training ground for survival training. Even though it had some vegetation that grew upon it, they weren't edible. The island was named after the philosopher Plato and was part of the Atlantis Project. (NF novel: Stone and Anvil)