A title given to Ulmo, one of the greatest of the Valar, whose province was the waters of the world, from streams to great rivers to the oceans. It was Ulmo who carried the Eldar into the West on the island of Tol Eressëa, and after the Exile of the Noldor, it was he who gave most thought to the plight of Elves and Men in Middle-earth. He became known as the 'Dweller in the Deep' (or occasionally 'Dweller of the Deep') because unlike the other Valar his halls were not in Valinor, but instead he dwelt beneath the dark waters of the Outer Ocean.