Helcaraxë

Helcaraxë, called the Grinding Ice, was the vast expanse of grinding pack-ice that closed the northern strait between Aman and the north-western shores of Middle-earth. It was reckoned impassable to all but the hardiest, lying between the twisted coasts of Araman and the Outer Lands. When Fëanor abandoned Fingolfin's host at Losgar, Fingolfin led his people across its perilous ice on foot into exile. The crossing was long and bitter, and it exacted a grievous toll on the marchers before the host at last reached Middle-earth.