This landscape is the product of many natural conditions coming together. In addition to the bitter cold air sweeping in from Siberia, the relatively low salinity of the sea’s surface layer and the limited exchange of water with the open ocean—because the sea is largely enclosed by land—make the sea prone to freezing. Ice formed in the northern seas grows as it drifts south toward the coast of Hokkaido. Drift ice is not only beautiful; it also supports a rich marine ecosystem. As sea ice forms, the circulation of seawater carries nutrients up to the surface, and phytoplankton growing beneath the ice become the starting point of a chain of life that extends to fish, marine mammals, and land animals.