Pancake ice is a form of ice that consists of round pieces of ice with diameters ranging from 30 centimetres (12 in) to 3 metres (9.8 ft), depending on the local conditions that affect ice formation. It may have a thickness of up to 10 centimetres (3.9 in).
Pancake ice features elevated rims formed by piling the frazil ice/slush/etc. up the edges of pancakes when they collide, both due to random bumping into each other and because of periodic compressions at wave troughs. These rims are the first indication of the onset of the formation of the pancake ice from less consolidated forms of ice.
Pancake ice may be formed in two ways. It may be formed on water covered to some degree in slush, shuga or grease ice. Alternatively, it may be created by breaking ice rind, nilas or even gray ice in the agitated conditions.