Chuuk Lagoon · Micronesia · Wreck · Night
Rio de Janeiro Maru
Two propellers still in place on a liner lying on its side
Photo: Motoki Kurabayashi · CC BY-SA 4.0
Rio de Janeiro Maru is a pre-war ocean liner that the Japanese navy turned into a submarine tender, now lying on its starboard side off Uman Island in Chuuk Lagoon. Its upper port side comes within 12 m (40 ft) of the surface while the hull rests on sand near 34 m, so one wreck offers both a shallow twilight dive and a deeper tour of the stern.
Also known as Rio De Janerio Maru, Rio.
Where it is and how deep
No published position for this site — the map shows Chuuk Lagoon and its other sites; operators know the mooring.
The dive
The wreck lies on its starboard side, so the port side forms the top of the dive at about 12 m (40 ft), a good place for a twilight or night dive. From there the hull falls away to sand at around 34 m (110 ft).
Two propellers are still in place, between 24 and 30 m (80 and 100 ft), and the massive stern gun is one of the wreck's most photographed features. The hold closest to the stern still carries sake bottles. Because the ship is on its side, the interior turns divers around, and some compartments are collapsing fast.
The wreck
- Vessel
- Rio de Janeiro Maru
- Type
- Ocean liner converted to submarine tender
- Built
- 1930
- Sunk
- 1944
- Cause
- Bombed by US carrier aircraft of TF-58 during Operation Hailstone
- Lies
- On its starboard side, with the sand at about 34 m
Mitsubishi Zosen Kaisha built Rio de Janeiro Maru in 1930 as an ocean liner for the Osaka Shosen Kaisha (OSK) Line. The navy had no use for a passenger liner and converted her into a submarine tender. On 17 February 1944 she lay at anchor east of Uman Island when TF-58 carrier planes bombed her during Operation Hailstone, and she sank on the 18th, just after midnight.
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
- Lying on its side, the interior is disorienting, and some compartments are collapsing rapidly.
Photos from Rio de Janeiro Maru
User: (WT-shared) Legis at wts wikivoyage · Public domain
Motoki Kurabayashi · CC BY-SA 4.0
Dive videos
Rio de Janerio Maru, Truk Lagoon. Dive this Japanese WWII shipwreck with Blue Lagoon Dive Shop. · PelagicProductionsUW on YouTube
Questions divers ask
Can Rio de Janeiro Maru be dived at night?+
Yes. The wreck lies on its side and the port side comes to about 12 m (40 ft), which makes it a good place for a twilight or night dive above the deeper stern.
Sources
- Rio de Janeiro Maru — Dive3D.eu
- Rio de Janeiro Maru — wrecksandreefs.com
- Wrecks — Truk Stop Hotel
Photo credits
- A long wreck hull lies on its side in deep blue water, its edge dotted with coral heads. by Motoki Kurabayashi, CC BY-SA 4.0, via Wikimedia Commons
- A diver with twin tanks enters the dark hold of a wreck, with green growth on the walls. by User: (WT-shared) Legis at wts wikivoyage, Public domain, via Wikimedia Commons
- Crates of old beer bottles packed in a wreck hold, seen from above under torchlight. by Motoki Kurabayashi, CC BY-SA 4.0, via Wikimedia Commons
More dive sites in Chuuk Lagoon
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Shrimp and goby burrows in the sand under the propellers
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Submarine periscopes still stacked in the holds
Trucks, a bulldozer and a tractor still parked in the hold
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