March 2013: Ice Diving, Shiretoko, Hokkaido, Japan


Saturday March 2nd 2013

Japan’s northernmost island of Hokkaido is a harsh environment in winter with huge amounts of snow and constant blizzards.  The wind is icy cold and the weather very changeable.  Yet even in an environment such as this, it is still possible to dive.   In February, frozen ice from the Sea of Okhotsk breaks up, detaches from the coast and is blown south by a northerly wind. Its journey ends at the northeastern Shiretoko Peninsula and marks the start of the ice diving season, an ideal opportunity for those who want to try something a little more adventurous.

The Shiretoko Peninsula is most well known for its unspoilt national parks with a variety of wildlife including brown bears and deer.  In winter however, it becomes a key area for observing drift ice, either through a short boat cruise or by diving.   Donning a dry suit and entering the ice is the gateway to a whole new experience.

Ice diving is not as difficult as it sounds but it is an advanced form of diving that is risky and there are several points to bear in mind.  Number one, you are diving in an enclosed environment with only one entry and exit point.   Although the layers of ice above you are floating, they are huge, heavy and close together, making it impossible to get out should you become lost.  Before the dive, a hole is dug and a small area is then created to set up equipment.   Through the hole goes a long rope which is fixed at around 3.5m.   Divers must never lose sight of it.

Number two is the incredibly high risk of hypothermia.  The water temperature is usually around 0 to -2 degrees and the dives are kept to within 10m.   The length of each will vary depending on how comfortable everyone is.  A 5mm hood and special thick gloves are essential and the dry suit must be zipped properly and double checked to prevent water seeping in.   If any diver feels cold, they must signal to ascend immediately, at which point their dive comes to an end.

Number three is the risk of equipment freezing.  When the pressure of air flowing from the cylinder into the first stage regulator is dramatically reduced, a lot of heat is lost as well.  The water surrounding the metal parts of the regulator is cooled and if the water is already very cold, as it is during an ice dive, it can cause the regulator to freeze.  A design with an environmental seal and a band that goes around the head securing the regulator firmly into the diver’s mouth can prevent this.  In addition to dry suits, weights and the usual equipment,  back-up scuba gear, tools to cut a hole into the ice, a shelter, rope, extra hoods and gloves must also be available in addition to a number of staff on standby, stationed around the hole.

Chashikotsuzaki, our dive site, is small and simple.  Out in the frozen open sea, our hotel was clearly visible in the distance as we held onto the rope and began to ascend, getting used to our dry suits, judging how much air was in them and practicing adding and releasing air accordingly.  The rope ended at 3.5m and before us was a collection of extremely large rocks.    With no current, crystal clear visibility and staff on hand, the dives were calm and relaxing.  At first glance the site doesn’t look exciting but a closer inspection of the rocks brought us to an array of small sea urchins, starfish and an collection of plain-looking anemones in addition to a tiny fascinating green shrimp with no English name, very well camouflaged against the bright green kelp.  The combination of sunlight and the extraordinary formation of the ice sheets above creates an interesting and ever-changing array of colour with a fascinating range of shades.  Around us, tiny species of jellyfish and plankton drifted slowly by but the highlight tends to be the ice at the surface, which reinforces the whole concept of ice diving as you look up and gaze in wonder and it offers some excellent photo opportunities as well.

For those more curious about the marine life, the star of the show is the Clione, a type of sea slug also known as a Sea Angel.  Its name fits perfectly.  An extremely tiny creature, almost a dot in the distance and impossible to spot, the Clione has a transparent body, wings and cute ears, making it look a lot like an angel.   It’s born swimming in the ocean and continues to do so until it dies, never once touching the bottom.  As it flaps its wings it almost seems to be flying, and is said to be able to survive a year without any food.  Usually they will eat other swimming sea snails.

If the spirit of adventure and unusual challenging diving appeals, then ice diving is an absolute must.  The day is more of an introduction and with a basic Open Water license anyone can have a go but courses are available for those who wish to train in earnest.  Given the extreme cold, not many are keen on trying again so most people who go ice diving tend to be repeaters and there are some good points –  in addition to the marine life, clear water and feeling of satisfaction at having attempted something different, a long soak in the hot spring and a cold beer afterwards makes the whole experience worth it.

Practical information

  • We took a direct JAL flight from Haneda to Memanbetsu at 17:55 which takes a little over 1hr 30mins (cost around 25,000yen return ticket)
  • At the airport we hired a car for the 2hr or so journey to Dolphin Hotel (Iruka Hotel) which is also a dive school.  Their website is:
  • Iruka Hotel is right next to the sea.  Outside is a separate area for baths (shampoo, shower gel etc provided, tiny changing room) and a car park.
  • The hotel is stunning and the facilities are excellent.  There are lockers for shoes, vending machines (beer 250yen), spacious dining area, outdoor deck, sea views from rooms, bookshelf and boots to wear for walking around in the snow
  • Rooms are en-suite with tatami floors and futons.  Free WIFI also available
  • Japanese-style breakfast begins at 7:30.  Fish, miso soup, rice, cabbage, egg, seaweed, cod roe, pickes….tea (Japanese style) and coffee available all day
  • Preparations for diving begin around 9:00.  The dive site can be seen from the dining area and is a short 10min walk away.  We put on our dry suits in the storage room and took the rest of our equipment (masks, fins, dive lights, cameras, hoods, gloves etc) to the dive site ourselves.
  • At the site, a rope is set to about 3.5m.  Entry is a short shallow walk to the hole, before holding onto the rope and sliding in.
  • The price (30,000 – 50,000yen, flights not included) includes 2 dives and all equipment rental.
  • After dive 1 there is an hour or so toilet/coffee break, weather depending.  After dive 2 and before dinner is some free time.
  • Staff will clean and look after all your equipment but you can bring your own masks, fins, dive lights or cameras.
  • Dinner is also Japanese style – rice, miso soup, raw fish, octopus, pickles, seaweed etc.
  • The day of the return flight is a non-diving day.  Because the weather changes rapidly and can get bad there are limited things to do but it’s possible to drive to a few souvenir shops to buy presents, go to a lookout point to take photos of the frozen sea, or take a cruise (the Aurora cruise, 3,500yen or so) for a close-up look of the ice.
  • The return flight to Tokyo leaves around 20:30

March’s dives

Dive 1: Chashikotsuzaki: depth: 4.9m, dive time: 34mins, water temp: 3.3C, entry time: 10:57AM, exit time: 11:35, average depth:  2.4m, used a 10L tank, dry suit and 5mm hood.  Saw the clione, starfish, sea anemones, short-spined sea urchins and comb jellies

Dive 2: Chashikotsuzaki: depth: 5.2m, dive time: 35mins, water temp: -0.5C, entry time: 13:07, exit time: 13:40, average depth: 2.2m, used a 10L tank, dry suit and 5mm hood.  Saw the clione, starfish, sea anemones, short-spined sea urchins, small thin fish called eelpouts, comb jellies and a green shrimp (kusairomoebi in Japanese)

11 thoughts on “March 2013: Ice Diving, Shiretoko, Hokkaido, Japan

  1. Magnus

    Hmm, how does breathing into the regulator before going into the water help? I would think that it would be the opposite; that breathing into it means that you get moisture into it, which in turn means that it may freeze up.


  2. Joey

    Hi~ I will planning the ice diving at Shiretiko next year Jan 2015, do you know any dive shop organize ice diving here and accept speak English diver? we will stay at the Iruka hotel, thanks


    1. Rising Bubbles Post author

      Hi Joey, thanks for the comment! The Iruka hotel is also a dive shop so you should be able to organise the dives directly with them. As for English speakers, I believe some English is spoken at Iruka hotel, or alternatively I would be more than happy to accompany your group as interpreter.


  3. vero

    Hi! i wanted to ask you if you need some diving licence or you can go with a instructor. Sorry about the bad english and thanks for the information!


    1. Rising Bubbles Post author

      Hi, thank you for the comment! You need a minimum licence of Open Water in order to join and you can go with an instructor. There is a group near Osaka that arranges ice diving trips in February, I can put you in touch with them. I last went in 2015 and there was a lot less ice so the group weren’t sure about future trips but I can find out. Let me know!


  4. Elaine

    I’ll be in Hokkaido from 30 December till 7 January and was wondering if there’s any chance that we could ice dive then? Will you be able to provide some advice please?



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