Chuuk Lagoon · Micronesia · Wreck
Heian Maru
Submarine periscopes still stacked in the holds
Area photo: Matt Kieffer · CC BY-SA 2.0
The largest wreck in Chuuk Lagoon: a 163-metre NYK liner converted to a submarine tender, lying on her port side with the upper sections at 12 metres and the bottom at about 33. Her holds are open and stacked with torpedoes and artillery shells, and like the rest of the fleet she is a designated war grave.
Where it is and how deep
7.3833° N, 151.8667° EApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
The dive
She lies on her port side in about 33 metres of water and at 163 metres long she is the biggest hull in the lagoon - Tonan Maru No. 3 was larger, but was refloated after the war. The upper sections come up to around 12 metres, so the dive starts shallow on what is now the uppermost flank and works along her length rather than down through her depth.
Inside, the cargo is a submarine tender's: stockpiles of torpedoes, artillery shells and submarine periscopes, along with numerous other items, in holds that can be entered. From within the ship the torpedo hole in the port side shows as a break in the plating. She is officially designated a war grave by the Japanese government, so nothing is taken and nothing is moved.
The wreck
- Vessel
- Heian Maru
- Type
- Ocean liner converted to submarine tender
- Length
- 163.3 m (536 ft)
- Built
- 1930
- Sunk
- 1944
- Cause
- Bombed and torpedoed by US carrier aircraft during Operation Hailstone
- Lies
- On her port side, upper sections at 12 m and the bottom at about 33 m
Heian Maru was launched at the Osaka Iron Works on 16 April 1930 and ran NYK's trans-Pacific service between Yokohama and Seattle before the war, after which she was converted to a submarine tender. US aircraft caught her at Truk during Operation Hailstone: she was hit by multiple pairs of bombs and by a torpedo dropped from a Grumman TBF Avenger, and sank on 18 February 1944. The Japanese government has designated the lagoon wrecks as war graves.
Marine life and season
The sources we used don't single out particular species here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prime | Prime | Prime | Good | Good | Fair | Fair | Fair | Fair | Good | Good | Prime |
Season follows Chuuk Lagoon: December to April is the dry season, driest from January to March; June to September brings the heaviest rain.
Dive videos
Diving Truk Lagoon - Inside the Heian Maru in 4K · Nomad Dive Logs on YouTube
チューク最大の沈船の船内は迷路 Truk Lagoon the Heian maru Penetration【 ミクロネシア チューク Chuuk Micronesia 】 · Chuuk Dive TREASURES on YouTube
Questions divers ask
Can a recreational diver dive the Heian Maru?+
Yes. The wreck is described as popular with moderately experienced divers: the upper sections start around 12 metres and the deepest part is about 33, which an Advanced Open Water diver comfortable with a deeper profile can handle. Going inside the holds is a separate skill set and needs wreck training.
Sources
- Heian Maru (1930) — Wikipedia
- Chuuk — Wikivoyage
- HEIAN MARU — combinedfleet.com
In The Logbook
- DPV diving: what an underwater scooter changesGear & kit · 10 min read
- WWII wrecks you can dive, by theatreWrecks · 7 min read
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