§ Of the Valar The Silmarillion

Nonetheless Ulmo loves both Elves and Men, and never abandoned them, not even when they lay under the wrath of the Valar. At times he win come unseen to the shores of Middle-earth, or pass far inland up firths of the sea, and there make music upon his great horns, the Ulumúri, that are wrought of white shell; and those to whom that music comes hear it ever after in their hearts, and longing for the sea never leaves them again. But mostly Ulmo speaks to those who dwell in Middle-earth with voices that are heard only as the music of water. For all seas, lakes, rivers, fountains and springs are in his government; so that the Elves say that the spirit of Ulmo runs in all the veins of the world. Thus news comes to Ulmo, even in the deeps, of all the needs and griefs of Arda, which otherwise would be hidden from Manwë.