The Sea of Helcar (also spelled Helkar) was a great lake or inland sea which existed in the central region of northern Middle-earth during the Years of the Trees.
In the beginning of Arda, the Valar created the Two Lamps and two great towers on which to place them. Melkor destroyed the Two Lamps, and where Illuin (the northern tower) had stood, the inland Sea of Helcar was formed. Many rivers flowed into the Sea of Helcar from the east. Cuiviénen, where the first Elves awoke, was a bay on the eastern side of the Sea of Helcar, and it lay under the shadows of the Orocarni (Red Mountains). During the Great Journey, the Elves travelled north around the Sea of Helcar before turning westward. After this, the Sea of Helcar passed out of history.