Rio de janeiro Maru - Chuuk (Truk) Lagoon

The *Rio de Janeiro Maru* is one of those wrecks that just clicks with us. It’s an enormous passenger-cargo vessel, over 140 meters long, lying on its starboard side, and it’s been well picked over by time and divers. We love poking around the upper decks, which sit in the shallower end of the dive, maybe 10 to 15 meters. Here, the sunlight really penetrates, illuminating sections of the promenade deck now covered in large plates of bracket coral. It’s a good spot to linger and watch the schools of fusiliers darting in and out of the superstructure. What we really enjoy, though, is the sheer scale of the cargo holds. Dropping into hold number 2, you're immediately struck by the rows of sake bottles still neatly stacked – a genuinely eerie sight. Further down, in holds 3 and 4, there are these huge steamrollers and trucks, just massive pieces of equipment that really give you a sense of the ship’s original purpose. Our favourite part has to be the engine room, though. It’s a bit of a squeeze to get into the deeper parts, but the massive engine components are captivating, and you often find big eye trevally circling in the gloom. This is a wreck for divers who appreciate history and don’t mind extended penetration – just make sure your buoyancy is dialled in.

Location: Chuuk (Truk) Lagoon, Micronesia, Central & South Pacific
Coordinates: 7.304172, 151.894130
Type: wreck

Best Time to Dive in Chuuk (Truk) Lagoon

The warmest water temperatures in Chuuk (Truk) Lagoon occur in January, averaging 28.9°C. The coolest conditions are in December at 28.9°C.

Monthly Water Temperatures

January: 28.9°C (air: 27.8°C)
February: 28.9°C (air: 27.7°C)
March: 28.9°C (air: 27.5°C)
April: 28.9°C (air: 27.5°C)
May: 28.9°C (air: 27.7°C)
June: 28.9°C (air: 27.5°C)
July: 28.9°C (air: 27.5°C)
August: 28.9°C (air: 27.7°C)
September: 28.9°C (air: 27.7°C)
October: 28.9°C (air: 27.9°C)
November: 28.9°C (air: 27.9°C)
December: 28.9°C (air: 27.9°C)

Nearest Dive Centres to Rio de janeiro Maru

Marine Life in Chuuk (Truk) Lagoon

Home to 213 recorded species including 133 reef fish, 36 hard corals, 17 sea cucumbers, 12 sea snails & nudibranchs, 5 sharks & rays, 4 clams & mussels.

Notable Species

Bristle-toothed Surgeonfish (Ctenochaetus striatus) - Reef Fish
Bleeker's Parrotfish (Chlorurus bleekeri) - Reef Fish
Bullethead Parrotfish (Chlorurus sordidus) - Reef Fish
Long-nosed Parrotfish (Hipposcarus longiceps) - Reef Fish
Blunt-head Parrotfish (Chlorurus microrhinos) - Reef Fish
Small giant clam (Tridacna maxima) - Clams & Mussels
Saddled Parrotfish (Scarus dimidiatus) - Reef Fish
Clown Tang (Naso lituratus) - Reef Fish
Black sea cucumber (Holothuria atra) - Sea Cucumbers
Greenfish (Stichopus chloronotus) - Sea Cucumbers
Schlegel's Parrotfish (Scarus schlegeli) - Reef Fish
Roundhead Parrotfish (Scarus globiceps) - Reef Fish
Dusky Parrotfish (Scarus niger) - Reef Fish
Blackspotted Sea Cucumber (Pearsonothuria graeffei) - Sea Cucumbers
Batavian Parrotfish (Scarus psittacus) - Reef Fish
Crown of thorns starfish (Acanthaster planci) - Starfish
Sea chub (Kyphosus cinerascens) - Reef Fish
Foxface (Siganus vulpinus) - Reef Fish
Banded maori wrasse (Cheilinus fasciatus) - Reef Fish
Unicornfish (Naso annulatus) - Reef Fish

Recommended Packing List for Rio de janeiro Maru

Based on average water temperature of 28.9°C.

Shorty or Rashguard - warm 29°C water needs minimal exposure protection
Mask - essential for every dive
Fins
BCD - buoyancy compensator
Regulator - your most safety-critical piece of gear
Dive Computer - tracks depth, time, and NDL
Surface Marker Buoy (SMB) - essential for boat pickups
Dive Torch - useful for crevices and colour at depth
Underwater Camera - capture your diving memories