The extraordinarily high productivity of the marine and terrestrial component of the property, produced and largely influenced by the formation of seasonal sea ice at the lowest latitude in the northern hemisphere, and the prominent interaction between the marine and terrestrial ecosystems are the key features of Shiretoko. The supply of nutrient-rich intermediate water resulting from the formation of sea ice in the Sea of Okhotsk allows successive primary trophic productions including blooms of phytoplankton in early spring, which underpins Shiretoko’s marine ecosystem. This in turn sustains the food sources for terrestrial species, including the brown bear and Blakiston’s fish-owl, through salmonid species swimming upstream to spawn. The property is globally important for a number of marine species, globally threatened seabirds and migratory birds.