Fast ice

[2] Seaward expansion is a function of a number of factors, notably water depth, shoreline protection, time of year and pressure from the pack ice.

In some coastal areas with abrupt shelf and no islands, e.g., in the Sea of Okhotsk off Hokkaidō, tides prevent the formation of any fast ice.

[4] The topography of the fast ice varies from smooth and level to rugged (when submitted to large pressures).

[6] Fast ice can survive one or more melting seasons (i.e. summer), in which case it can be designated following the usual age-based categories: first-year, second-year, multiyear.

[2][5] Fast ice may be delimited or enclose pressure ridges which extend sufficiently downward so as to be grounded—these features are known as stamukhi.