The island of Hokkaidō, Japan’s northernmost island, features a cool to subarctic climate in the far-north.
Nutrient-rich, cold currents coming from the north means it mostly cold-water diving all year around, but some areas do warm up a little in the summer months.
On the west side of the island for instance, the Shakotan Peninsula offers a dynamic rocky topography, and clear blue waters known as Shakotan Blue, with dramatic temperature changes going from roughly 3°C in winter to 24°C in summer.
MAIN DIVING AREAS MENTIONED
- The Shiretoko Peninsula, at the easternmost portion of Hokkaidō island, protrudes into the Sea of Okhotsk (Hokkaidō Prefecture)
- Lake Shikotsu, a freshwater caldera lake in Chitose, which belongs to the Shikotsu-Toya National Park (Hokkaidō Prefecture)
- The Shakotan Peninsula, on the west side of the island, is a mountainous peninsula projecting almost 30 km into the Sea of Japan
DIVING HIGHLIGHTS AND ICONIC MARINE LIFE
Around February, ice floats from the Sea of Okhotsk start heading down towards Hokkaidō’s Shiretoko Peninsula, to the east of the island, where it is possible for divers comfortable with drysuit diving to brave the cold and dive under the floating blocks of ice, usually from February to March.
Water is at or just below the freezing point, around 0 to -4°C, but often offers 20m+ visibility.
As with most other forms of ice diving, contraints like having to rely on a entry/exit point means that divers must stay close, with a designated area and no deeper than 10m, with a 30 minute max dive time.
ENDLESS FRESHWATER VISIBILITY
Hokkaidō’s Lake Shikotsu, a caldera lake, is reputed to offer the clearest fresh water visibility in Japan, with 25m+ as an average minimum, to near endless… The lake does not freeze over and can be dived all year round, and it is sometimes possible, in season, to see spawning events of red salmon and trouts, which make their way upriver and into the lake.
Hokkaidō also offers possibilities to dive kelp-forest environments (in Shiretoko’s Rausu, or Hakodate’s Usujiri sites, for instance) and interesting caverns/caves.
ICONIC MARINE LIFE
Hokkaidō marine life highlights include the sea angels (Clione limacine), also known as Clione or Ice fairies, small (= cute!) translucent sea slugs, basically free-swimming jellyfish hovering under the ice floats by flapping their wings. They are mostly spotted between January and March in the Shiretoko Peninsula.
Another local favourite is the cute (?) or at least odd-looking smooth lumpfish/lumpsucker (Aptocyclus ventricosus) and other small Cyclopteridae, which can be spotted around Hokkaidō dive sites in the winter months
Another local iconic species is the North Pacific giant octopus (Enteroctopus dofleini), which, on the other side of the Pacific, has made Canada’s Vancouver island diving famous.
Juveniles will usually avoid divers, but adult octopus are very curious, especially about divers with cameras sporting long strobe arms, which they will often try to pull away…
Other marine life commonly encountered in Hokkaidō are crabs (including the Red king crab or Kamchatka crab, (Paralithodes camtschaticus), which can be encountered in certain areas of Hokkaidō, and good macro critters including nudibranchs, sea urchins starfish and shrimps found on the a seabed strewn with anemones, rock formations, and boulders.
Temperature changes and the rich nutrients carried into by currents mean that there species found in Hokkaidō’s waters do change a lot between seasons, and there are large seasonal spawning feed/events for various fish species.
Larger size marine animals are also sometimes spotted in Hokkaidō, including marine mammals such as Harbour seals (Phoca vitulina), Steller sea lions (Eumetopias jubatus), Dall’s porpoise (Phocoenoides dalli), orcas (Orcinus orca), Berardius/Baird’s beaked whale (Berardius bairdii) and other migrating whales and cetaceans.
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