Island on the western coast of Beleriand, near to the coast of Arvernien. It was safe from the forces of Morgoth, who had few ships and could not take on the navies of the Teleri. As a result, it became a haven for elves after the Nirnaeth Arnoediad and especially the fall of Vinyamar and Eglarest, when Cirdan used his ships to transport survivors to the island.
It features in Tolkien's book, The Silmarillion.
It was located in the Bay of Balar. There may be an etymological link between Balar and Beleriand.