To mariners, ice has many different forms. Certain kinds of ice can stop a boat in its tracks. Other kinds of ice give the ocean an oily appearance and reflect certain parts of the daytime or night sky. Oceanic ice, in all its forms, almost constitutes a science in itself. This article is about the kinds oceanic ice, and their effect on boats and the ocean's surface.
Oceanic ice can be a day or several years old.
Depending on its age, ice can be anywhere from half an inch to 40 feet thick, in the case of icebergs. Ice contains many different states of formation within these categories. Young ice exists in many forms. It can be thin and covering the surface like an oil sheet, or thicker and slushy, as in the case of Nilas and pancake ice. Frazil ice is often deceptive, because it gives the ocean a slick, oily feel.