§ Of the Ruin of Beleriand and the Fall of Fingolfin The Silmarillion

Now when Turgon learned of the breaking of the leaguer of Angband he would not suffer any of his own people to issue forth to war; for he deemed that Gondolin was strong, and the time not yet ripe for its revealing. But he believed also that the ending of the Siege was the beginning of the downfall of the Noldor, unless aid should come; and he sent companies of the Gondolindrim in secret to the mouths of Sirion and the Isle of Balar. There they built ships, and set sail into the uttermost West upon Turgon's errand, seeking for Valinor, to ask for pardon and aid of the Valar; and they besought the birds of the sea to guide them. But the seas were wild and wide, and shadow and enchantment lay upon them; and Valinor was hidden. Therefore none of the messengers of Turgon came into the West, and many were lost and few returned; but the doom of Gondolin drew nearer.