What event destroyed the island kingdom of Númenor in J.R.R. Tolkien’s legendarium?

The Downfall of Númenor destroyed the island kingdom of Númenor in J.R.R. Tolkien’s legendarium.

Númenor was an island realm granted to Men who had aided the Elves during the wars against Morgoth. Over time, its people became increasingly jealous of the immortal Elves and fearful of death. Under King Ar-Pharazôn, Númenor challenged the power of the Valar and prepared to invade the Undying Lands.

The Valar appealed to Eru Ilúvatar, who changed the shape of the world. Númenor was overwhelmed and sank beneath the sea, while Aman was removed from the ordinary world. Elendil and other Faithful survivors escaped and later founded Arnor and Gondor in Middle-earth.

The event is sometimes compared with the Atlantis story because both involve a proud island civilization destroyed by catastrophe. Tolkien’s account, however, is part of his own mythology and connects directly to the later history of Sauron, Gondor, and the shape of the world.