Drift Ice Diving
Ice floes that drift into the Nemuro Strait every winter provide novel diving opportunities for experienced divers. Diving tour operators cut entry points into the ice with a chainsaw, and divers can slip below the ice in a dry suit to view life beneath the floes. Northern marine life is different from that of warm water oceans, and divers can expect to see cold-water species such as clione—translucent sea slugs commonly called sea angels.
Opportunities for diving under drift ice are relatively rare worldwide. Ice floes are generally restricted to locations around the poles and rarely form at lower latitudes. However, floes occur annually in the Sea of Okhotsk, off the coast of northern Hokkaido. They form because freshwater from Russia’s Amur River flows into the sea, diluting the salt content and raising the freezing point. The Sea of Okhotsk freezes around the mouth of the Amur River before breaking apart and flowing south towards the Rausu coast.
The ice-diving season is between February and March, and open water certification is required to join a diving excursion. Due to the freezing water temperatures, each dive is limited to around 20 minutes. One tour company offers ice-diving experiences; ask at the tourist information counter for more information. Tour company staff can give basic instruction in English. Note that reservations are required at least 24 hours in advance.