It takes some serious cold for salt water to turn to ice. Sea ice forms first in coves where there is an influx of fresh water as the salt content of the sea water is diluted. From the coves and shores, the sea ice gradually expands outward, provided there are no high winds (and therefore waves) to break it up and drift it away. In periods of calm, large fields of ice may form at high tide. As the tide recedes, the ice is left broken on the rocks.