Chuuk Lagoon · Micronesia · Wreck
Sankisan Maru
Mast tips reach to within 5 metres of the surface
Photo: mattk1979 · CC BY-SA 2.0
A 112-metre freighter torpedoed off the west coast of Uman on 18 February 1944 and lying about 350 metres offshore. The upper deck sits at 18 metres and the bow, still upright, at 30, so most of the ship is inside recreational range, and the holds are still stowed with aircraft parts, trucks, tractors and ammunition.
Also known as Yamakisan Maru.
Where it is and how deep
7.2939° N, 151.8659° EPublished position for this site.
The dive
Mast tips come to within about 5 metres of the surface, which makes both the descent and the safety stop easy - you hang on rigging rather than in open blue water. The upper deck is at roughly 18 metres and the bow, sitting upright, at 30. A twin machine gun and a cannon are mounted on the forward deck, at the shallow end of the ship.
The holds carried weapons, aircraft parts, tractors, trucks and ammunition, including grenades and artillery shells, and much of it is still stowed where it was loaded. The stern is a separate proposition: it runs down to about 50 metres, and in 1974 a piece of unexploded ordnance found during salvage work was detonated there. Munitions recovered from the ship were afterwards used to blast passages through the surrounding reef.
The wreck
- Vessel
- Sankisan Maru
- Type
- Passenger and cargo ship
- Length
- 112 m (367 ft)
- Built
- 1920
- Sunk
- 1944
- Cause
- Torpedoed during Operation Hailstone on 18 February 1944
- Lies
- Upright about 350 m off the west coast of Uman Island
Built in the United States in 1920 - sources disagree on whether she started life as Estero, Red Hook or Commercial Traveler - the 4,752-ton ship was carried in Japanese service as Sankisan Maru, also written Yamakisan Maru. She anchored near the west coast of Uman Island on 17 February 1944 and was struck by a torpedo the following day during Operation Hailstone, sinking rapidly where she lay.
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.
Know before you go
- Live ordnance is part of the cargo: grenades and artillery shells sit in the holds, and unexploded ordnance was detonated in the stern in 1974. Nothing here is handled or moved.
- The stern drops to about 50 metres while the deck sits at 18, so it is easy to run deeper than planned - agree a maximum depth before you drop in.
Photos from Sankisan Maru
montereydiver · CC BY 2.0
David Burdick / NOAA Photo Library · Public domain
mattk1979 · CC BY-SA 2.0
Dive videos
Diving Truk Lagoon: Sankisan Maru · Diving Videos on YouTube
Questions divers ask
How deep is the Sankisan Maru?+
The mast tips are about 5 metres below the surface, the upper deck sits at roughly 18 metres and the bow at 30. The stern runs down to around 50 metres, beyond recreational limits, so most dives stay on the forward part of the ship.
Sources
- Sankisan Maru — Wikipedia (German)
- Operation Hailstone — Wikipedia
Photo credits
- A coral-encrusted mast of the Sankisan Maru rising against blue water by mattk1979, CC BY-SA 2.0, via Openverse
- A ship's wheel silhouetted inside the Sankisan Maru by montereydiver, CC BY 2.0, via Wikimedia Commons
- Vivid pink soft coral growing on the Sankisan Maru wreck by David Burdick / NOAA Photo Library, Public domain, via Wikimedia Commons
- A diver descending into the cargo hold of the Sankisan Maru by mattk1979, CC BY-SA 2.0, via Openverse
In The Logbook
- Why do you pee when diving, and tire after?Body & health · 12 min read
- Do you need a safety stop? What it buys youBody & health · 11 min read
- WWII wrecks you can dive, by theatreWrecks · 7 min read
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