Sea-longing

Sea-longing, or the Unquiet of Ulmo, was a strong desire to return to the sea that typically affected the Eldar.
The Noldor who lingered in Middle-earth had an unquietable yearning for the Sea, coupled with their nostalgia of their home. It was slumbering in the hearts of the Sindar, until it awoke after seeing Belegaer, the Great Sea to the west of Middle-earth, for the first time. The cry of the gulls awakened the sea-longing in Legolas' heart when he heard them at Pelargir.
Tuor first felt the sea-longing when he looked upon Belegaer, and he felt it ever afterwards. This longing was also passed on to his son, Eärendil. In addition, those that heard the music of the Ulumúri, the horns of Ulmo, would always feel a longing for the sea.