August 2012: The Chinsen, Atami, Shizuoka Prefecture, Japan

Saturday August 25th 2012

Atami is 40 minutes away from Tokyo by bullet train, and isn’t really considered a dive destination.  Much more famous for being a hot spring town (Atami means “hot ocean”), volcanic water pumps up from the ground in many locations.  The town is certainly not the first place that comes to mind when looking for somewhere to dive, but there is actually much more to the sea than we think.  Soft corals, octopus, nudibranchs, and a variety of fish have all been spotted at the town’s two main dive sites and one of the only divable wrecks, the Chinsen or quite literally “shipwreck,” can be found here too.  The Chinsen’s real name was actually the Asahi Maru, a barge that sank some 20 years ago in a typhoon.  The typhoon was so strong that the barge split in two, and it now lies in two parts about 15m apart, at a depth of around 25-30m.  It is considered a spot for certified advanced divers firstly because of its depth, and also because there can be slight currents at the surface and entry is off a boat and down a long rope with nothing to see until the wreck appears.  For a diver more used to shore entries and being surrounded by rocks and coral during a descent, such an entry can be a little daunting.

We began with a warm up dive at Soudaine, one of Atami’s main dive sites.  After a short 10min boat journey and backward roll entry, there are some famous rock pinnacles that lead down to around 40m.  At just over 23m, we turned left next to one huge wide rock covered with anemones and soft coral.  Taking a right turn around this rock, we ascended slightly and soon came into warmer waters.  Here visibility was much better and looking up it’s possible to see several pinnacles stretching towards the surface.  These are clustered together and from deeper depths it’s like looking up at several large mountains or valleys.  The entire area was teeming with fish and several moray eels darting here and there.  Visibility was excellent, but unfortunately the current was strong and the remainder of the dive became a drift dive as we returned the way we came, clambering over the rocks towards the ascent point.

We kept these conditions in mind as we headed to the Chinsen.  Part of my Advanced training, the wreck is north of Soudaine and next to Bitagane, another main dive site of impressive walls leading down to 40m, and teeming with anemones, clown fish (at 20m or so), moray eels, amberjack, Moorish Idols and many others.  The descent is down a long rope connected to a single buoy, and the Chinsen comes into view at around 21m.  It’s an 85m-long barge split in two, and the dive begins with the hulk and front area.  The key to diving the Chinsen is to go slightly deeper so you are at the side of the boat and not over it.  At 25m, with a torch at hand, many discoveries await.  Moray eels nest in the nooks and crannies, Margarita basslets and halflined cardinals swim by, and sea fans grip the surface of the wreck, which is also 100% packed with sponges, nudibranchs and spider crabs.  The wreck itself is very easy to navigate.  We turned at a 45 degree heading and followed the sides until the back of the wreck. From here, simply follow the structure which eventually leads back to the starting point.  The current is mild but noticeable so it’s important to stay close to the wreck.  Directly below the rope and entry point is a garden of soft coral, and home to schools of fish that dart by as a torch is shined over them.

The Chinsen has many holes, entrances and pathways through which penetration is possible, but when doing so, depth and time spent underwater must always be remembered.  There is also the risk of getting tangled in something or running low on air as exploring the wreck becomes the diver’s main focus.  Loose parts can also fall if there is any kind of disturbance, for example rigorous fin kicking or air bubbles, which is why divers are highly recommended to train first before attempting to enter a wreck.  As the Chinsen is relatively deep, it’s also important to know your rock bottom pressure, turnaround pressure (to be discussed with your buddy), and make the required safety stops along the rope as you ascend.

As beautiful as a dive site may be, the ocean is perilous and scuba diving carries with it some inherent risks.  The Chinsen is no exception, but although it’s a site for advanced divers, an experienced Open Water diver could cope with the conditions.  Many people think of scuba diving in warm tropical locations, but within easy access from Tokyo are some beautiful dive sites in terms of biodiversity.  Atami, The Chinsen and other sites I have explored this summer, really are some well-kept secrets of Japan’s diving world.

Practical information

  • To get to Atami, take the Shinkansen bullet train from either Tokyo or Shinagawa stations.  The early morning train from Shinagawa leaves at 7:34 (destination Nagoya) and arrives at Atami around 8:12.  A single ticket with non-reserved seat costs around 3500yen.  It’s advisable to arrive around 8AM to have a full day of diving.
  • My dive group picked us up and took us to Atami Scuba (, a 5-7min drive from Atami station.  The school is right on the port, with hot showers and toilets, a vending machine by the reception (500 ml bottle of water 150yen), and a fairly large area with benches and picnic tables for barbecues and for hanging equipment.  No tea, coffee and snacks are provided so remember to prepare some. There is no convenience store near the dive school, only a couple near the station which is up a hill and difficult to get to.  Barbecue was offered by my dive group.
  • The boat leaves for the first dive between 10 and 10:30.  After arriving, getting equipment and being shown around the facilities, it’s best to start gearing up right away.  Everyone puts on their equipment and walks on to the boat to sit on the floor.  Entry into the water is a backward roll.
  • After the first dive there is usually a 1.5 to 2 hour break, before the next dive begins in the early afternoon, around 13:30 or 14:00.
  • Two boat dives cost 15,000yen (rental gear separate).  The group barbecue is 1200yen.  Train tickets and any overnight stay in Atami are not included.
  • All divers are responsible for setting up their equipment, washing it and tidying up after each dive.  Heavy suitcases containing diving equipment can be left in the shower rooms for those staying overnight.

August’s dives

Dive 1: Sodaine: depth: 24.7m, dive time: 30mins, water temp: 23C, entry time: 10:55, exit time: 11:25, average depth: 14.2m, used a 12L tank, 5kg weights (2kg in belt and 3kg metal plate) and 5mm wetsuit.  Start pressure: 190 bar, end pressure: 40 bar.  Saw soft coral, Moorish Idols, moray eels and various nudibranchs.

Dive 2: The Chinsen: depth: 27.8m, dive time: 29mins, water temp: 23C, entry time: 13:41, exit time: 14:10, average depth: 16.8m, used a 12L tank, 5kg weights (2kg in belt and 3kg metal plate), and 5mm wetsuit.  Start pressure: 180 bar, end pressure: 40 bar.  Saw margarita basslets, halflined cardinals, more soft coral, anemones, and amberjack.

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