Númenor is the fictional island kingdom destroyed in the Second Age of J.R.R. Tolkien’s legendarium.
The island was raised from the sea by the Valar as a reward for the Edain who aided the Elves during the wars against Morgoth. Its people, the Númenóreans, were granted unusually long lives and became powerful sailors. Over time, however, fear of death and imperial ambition grew among their kings.
The final king, Ar-Pharazôn, attempted to challenge Sauron and later sailed against Valinor. In response to this rebellion, Eru Ilúvatar changed the shape of the world and caused Númenor to sink beneath the sea. Elendil and his sons survived and founded the realms of Arnor and Gondor in Middle-earth. Númenor is sometimes compared with Atlantis, but it belongs specifically to Tolkien’s own mythology and has its own detailed history.