Greenland halibut (US: Greenland turbot). A huge, side-swimming flatfish found in the deep waters of the North Atlantic. The skin is dark grey or brown. It is often smoked as it has dense, oily flesh. We went for a lovely walk once at a place rather ludicrously called Halibut Point, not so very far from Cape Cod. At a very short distance from the shore was a deep and utterly tranquil freshwater pool, full of turtles. No halibut that we could see.