Old ice which has survived only one summer's melt. Because it is thicker and less dense than first-year ice, it stands higher out of the water. In contrast to multi-year ice, summer melting produces a regular pattern of puddles. Bare patches and puddles are usually greenish-blue.
The regular pattern of puddles produced during the melt season is only a feature of Arctic se ice. Melt water does not usually accumulate on the surface of Antarctic sea ice.
Second-year ice is the most common form of old ice present in Antarctica.