Fast ice forms and remains ‘land fast’ along the coast, where it is attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea level.

Fast ice acts like a belt around the Antarctic coast, regulating the flow of ice shelves and glaciers into the sea.

Fast ice may be formed in situ from seawater or by freezing of pack ice of any age to the shore. It may extend a few metres or several hundred kilometres from the coast.

If fast ice is more than one year old, it is prefixed with the appropriate age category (old, second-year, or multi-year).

Scientists have been monitoring fast ice in East Antarctica since the 1950s. Ice cores form a long-term record of East Antarctica fast ice and are used in science projects. Basic information on the cores is recorded in the field, before they are taken back to Australia for detailed analysis.

Fast ice is an important habitat. In spring, zooplankton feed on the nourishing algae found in the fast ice. Emperor penguins breed on fast ice, and Weddell seals give birth on it.