What is legendary island and utopia which according to Plato was swallowed by earthquake?

Legendary Island, often associated with the concept of Utopia in Plato's works, refers to the mythical island of Atlantis. According to Plato, Atlantis was a powerful and advanced civilization that existed around 9,000 years before his time. It ultimately fell out of favor with the gods and was swallowed by the sea due to a catastrophic earthquake. This tale serves as a philosophical allegory about the rise and fall of societies and the pursuit of an ideal state.