August 2013: Kozushima, Japan

Wednesday August 7th to Friday August 9th 2013

Legend has it than in ancient times the gods of the Izu islands met on Kozushima to discuss how to share freshwater but legend and history are not the only things the island is known for.  About 3 hours and 45 minutes away from Tokyo, it’s an ideal destination for a summer weekend break, a tiny paradise that bubbled up from the Pacific Ocean a very very long time ago.  Less touristy than the other islands in the Izu island chain, Kozushima is particularly peaceful with a population of fewer than 2,000.  It’s also relatively flat and its beautiful white sand beaches make it ideal for divers, swimmers and snorkelers alike.  I spent two days on Kozushima and visited the following dive sites:

Saima:  Saima begins at 5m over rocks and boulders teeming with marine vegetation.  The dive is not so exciting to begin with but the best always comes last.  Home to a collection of rocks and boulders, the highlight of Saima are two gigantic structures stretching down to about 20m with dark spots, tiny holes, mini caves and an interesting route to swim through.  It soon becomes obvious that life is abundant here and as we travelled slowly, exploring the walls, something always swam past in every direction – puffer fish and boxfish hovered close by, tiny box fish darted in and out of sight, colourful nudibranchs stuck to the walls feeling the mild current and no doubt enjoying the warm temperature and two trumpet fish appeared looking very chilled out.  At the end of the dive, a school of yellowtails swam by out of nowhere, frantically disappearing into the distance, no doubt in search of the day’s meal.  This is an excellent dive for those who aren’t so confident clearing their ears as you can stop during the descent and use your light to explore the walls.

Akasaki:  This is Kozushima’s most popular spot for swimming, snorkeling, try dives and training.  It’s an easy-going experience with warm temperatures, great visibility and mellow currents.  Divers carry their tanks and walk down a flight of steps to the water before donning masks and fins and swimming to about 6m.  The dive takes you over a sheltered sandy and rocky terrain, a carpet of medium-sized rocks.  Akasaki is very sheltered and a macro lover’s paradise.  Hovering overhead and moving as slowly as possible, we found a fantastic array of tiny life forms, an abundance of adult and baby sea slugs, tiny nudibranchs, starfish, crabs dragging themselves across the rocks and various critters curiously poking their heads out of tiny holes in the rocks.  Fish such as bluespotted cornet fish and oriental butterfly fish drifted by, nibbling at the rocks and watching us closely, no doubt used to the large number of swimmers and snorkelers.  This dive is warm, easy, very relaxing and most fun if you have a camera.

Hiradan Arch:  A 5-minute boat ride from one of Kozushima’s main ports , a cluster of rocks in the open sea looks like a promising site for an exploratory dive.  We descended directly to around 17m and arrived at a huge cave-like structure although it wasn’t a cave, simply a large area with walls caked in nudibranchs and other macro life.  Hiradan Arch reveals an interesting world of nudibranchs clinging to walls of rock and flashing their exotic colours.  We descended past a wall of life, and wrasses (clown coris), groupers (gold ribbon groupers) and blackmouth goosefish swam here and there aggressively, darting into the nearest hiding place at my approach.  The dive can get monotonous as there is nowhere else to go other than the huge cave-like structure but the sun pours in making visibility excellent and it’s a superb place for divers into macro life who want to take close up shots. We saw some extremely flamboyant nudibranchs (ceratosoma trilobatum and phyllidiella pustulosa)

Sanju:  Below the water here is an aquarium-like world packed with fish such as white-saddle goatfish, spotted tail morwongs and golden-striped groupers.  Sanju is a relatively easy dive site (maximum 20m or so) with much to offer despite appearing to be relatively standard at first glance.  Divers descend freely to about 5m of rock teeming with anemones and other critters such as sea goldies twitching over holes and cracks.  Spider crabs are also around, stretching their long legs.   Down at 12m there are more huge rocks that reach up to the surface, full of fish and anemones.  The best part of this dive is the 12-15m area where the sun penetrates best and the water flow is quite smooth making it easy to hover and get some good photos.  Doing the safety stop over the rocks makes for better buoyancy control too.

Arima: This is a sheltered bay only accessible by boat.  There are even a few dolphins – we encountered a mother and baby at the surface.  The rocks here are spread out at around 8m and there is a great sandy area at around 12m where you can literally rest face down and look up at the sun streaming through the water.  We spent a good 15 minutes or so scanning the water, waiting for anything to roll in.  With rocks and boulders to our left, we swam across this sandy area and after rounding a corner an incredible site materialized in the distance – a school of goatfish perfectly ordered and resting on the sand in the slight current.  Unbelievably tame, they watched us intently and even let us swim directly above them as we continued on our journey.  The rocks were full of life – eels displaying their menacing jaws, a bright yellow baby box fish appearing like a ray of sunshine and a round ribbontail ray devouring its latest meal.

Tsumari:  Night dive fans will enjoy Tsumari, 5 minutes from the dive school and located at the bottom of a cliff with a small set of steps leading into the water.  Divers walk down the steps carrying their tanks, put on their fins and masks in the water and swim out.  Conditions were perfect for a night dive with flat seas and good visibility.  The bottom is completely sandy. We turned left and began exploring a cluster of small rocks.  The current increased here and we swam straight out with it before reaching an area of concrete beams, perhaps placed there deliberately.  Luckily for us, lobsters blanketed the entire area which made for an amazing start and the beams are home to an array of life, mainly interesting looking shrimps as well as sleeping fish.  The dive is not deep and is fantastic for marine life.  We even spotted an octopus emerging from behind a rock and a huge sea snake slithering away under the glare of our flash lights.  The lights also illuminate some strange and amazing planktonic critters attracted to the glow which gives the dive a nice end as you can sit on the sand, wave your flashlight about and enjoy the show.

Practical information

  • I took the fast jetfoil ferry from Atami near Tokyo with Tokai Kisen ferries (  The boat leaves at a convenient 11AM and arrives at Kozushima around 13:00.  A single ticket costs 6,390yen.  There is one vending machine on the ferry and the seats are just like airplane seats.  Bring something to eat and a book to read too.
  • I booked my accommodation through the Kozushima Tourist Office (04992-8-1111) on the advice of Tokai Kisen ferries.  The tourist office found me an inn called Daimatsu ( charged 13,600yen for two nights for a basic room, dinner and breakfast consisting of rice, miso soup, fish, vegetables and pickles.  Dinner begins at 19:00, breakfast is around 7:00 and everyone eats in the communal room.
  • I booked my dives with Nangoku (  Four boat dives and two beach dives comes to just under 40,000yen including tanks, weights and a guide.  The school organizes an excellent night tour of Kozushima and give advice on places to eat or buy souvenirs.
  • A representative from my accommodation came to pick me up at the port and drive me to the inn for check-in.  The inn is about 2mins drive from the port.  The dive school called me soon afterwards and I walked there to prepare for my first dive.  This took about 5mins.
  • Diving equipment can be sent in advance from Tokyo for about 2,500yen using Kuroneko Takkyubin.
  • Immediately upon entering Nangoku you see a huge table with shelves of books, walls of photos and other decorations all around, with the reception desk to your left.  The area for diving equipment (washing, drying, hanging, storage) is up on the deck upstairs overlooking the sea.  A toilet, two showers and a changing room area are also on the deck.  Tea is available as are diving and fish books/magazines .
  • After loading the van with equipment and getting changed into our wetsuits, we drove to the dive sites.  The boat is very spacious and flat with almost no indoor area but a good few places to sit outside next to the engine in the middle.  Equipment is put on when the boat arrives at the dive sites.  Bring your own towel, sunscreen and snacks for the boat journey.
  • Lunch is not provided but after each dive there is a chance to go to a couple of cute restaurants/cafes practically next door to the dive school.
  • Divers are responsible for looking after their own equipment.  When the dives are over, they are free to use the deck to change, wash, hang, dry etc as they like.
  • There are a couple of nice restaurants/bars near the dive school and inn but these close quite early (around 21:30).  Between the port and Akasaki beach is a wonderful outdoor hot spring which Nangoku will book for you and take you to if interested.

August’s dives

Dive1: Saima: depth: 15m, dive time: 41mins, water temp: 30C, entry time: 13:55, exit time: 14:35, average depth: 10m, used a 10L steel tank, 5mm wetsuit and 3kg back plate (no extra weights).  Start pressure: 200 bar, End pressure: 70 bar.  Saw silver-stripe round herrings, eels, spiny lobster, morwongs, porcupine fish, greater amberjacks, sea chubs, trumpet fish, rock porgy, boxfish, abalone, white-lined goatfish, cow fish, Pacific burrfish, spotted tail morwongs, axilspot hogfish.

Dive 2: Akasaki: depth: 5.6m, dive time: 47mins, water temp: 30C, entry time: 15:38, exit time: 16:25, average depth 3.5m, used a 10L steel tank, 5mm wetsuit, 3kg back plate and 1kg extra weight in pocket.  Start pressure: 200 bar, End pressure: 110 bar.  Saw starfish, thalassoma cupido (wrasses), sea biscuits, oriental butterfly fish, bluespotted cornet fish, sea slugs and surgeon fish.

Dive 3: Hiradan Arch: depth: 17.5m, dive time: 39mins, water temp: 29C, entry time: 09:41, exit time: 10:19, average depth 11.4m, used a 10L steel tank, 5mm wetsuit, 3kg back plate and 1kg extra weight in pocket.  Start pressure: 200 bar, End pressure: 70 bar.  Saw blackmouth goosefish, sea slugs (ceratosoma trilobatum, phyllidiella pustulosa), eels, clown coris (wrasses), gold ribbon groupers and another seaslug (phyllidiaocellata).

Dive 4: Sanju: depth: 14.9m, dive time: 42mins, water temp: 30C, entry time: 11:13, exit time: 11:55, average depth: 10m, used a 10L steel tank, 5mm wetsuit, 3kg back plate and 1kg extra weight in pocket.  Start pressure: 200 bar, End pressure: 65 bar.  Saw sea slugs (hypselodoris zephyra), silver-stripe round herrings, sea goldies, morwongs, spider crabs, white-saddle goatfish, spotted tail morwongs and goldenstriped groupers.

Dive 5: Arima: depth: 15.3m, dive time: 48mins, water temp: 29C, entry time: 13:59, exit time: 14:47, average depth: 11.8m, used a 10L steel tank, 5mm wetsuit, 3kg back plate and 1kg weight in pocket.  Saw round ribbontail rays, whip coral gobies, box fish, red lionfish, white saddle goatfish, thread-sail filefish, blackalls, cowfish, boxfish, pufferfish and Christmas tree worms.

Dive 6: Tsumari: depth: 7m, dive time:51mins, water temp: 28C, entry time: 20:22, exit time: 21:11, average depth: 4.9m, used a 12L aluminium tank, 5mm wetsuit, 3kg back plate and 2kg extra weight in pockets.  Saw prawns, porcupine fish, Japanese spiny lobster, octopus, sea congers, Pacific burrfish, anemone hermit crab, parrotfish and wedge sea hares.

2 thoughts on “August 2013: Kozushima, Japan

  1. Oswin

    Excellent place to visit. Went there a couple of weeks back. Unfortunately, the sea was rough and could only dive Akasaki. Made a video from my visit


    1. Rising Bubbles Post author

      Hi Oswin, so glad you got to visit, it’s a great place isn’t it? Shame about the rough seas but hopefully you’ll have another chance to visit if you are based in Japan. There are some nice dive spots out there. Will check out your video…



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s