Guardian: What is sea ice? Frozen sea water. Unlike the mighty ice sheets and glaciers that rest on the bedrock of Greenland and Antarctica, sea ice forms and melts on the surface of the ocean. The amount of sea ice waxes and wanes with the seasons. It forms in the winter and melts in the summer. Where is it found? In the deep south and the far north. Only the freezing conditions of a polar winter are harsh enough to freeze seawater on a large scale. Sea ice in the Arctic gets …