An ancient sea formed by the fall of the mountain holding Illuin, northernmost the two lamps that first lit the world (S/49). The meaning of this name is unclear, but it probably is an elaboration of helca “icy, ice-cold” (SA/helca).

Conceptual Development: In the earliest Lost Tales, ᴱQ. Helkar was the name of the pillar holding one of the lamps, the southernmost one (LT1/69). In Silmarillion drafts from the 1930s, the name ᴹQ. Helkar was applied instead to the northern lamp, also used for the name of the sea left behind by its destruction (SM/256, LR/261). In Silmarillion revisions from the 1950s-60s, the name of the northern lamp was changed to Illuin, and Helcar became the name of the sea only (MR/7, 22 note #6).