Dive Site: Rio de Janeiro Maru

Dive site facts: Rio de Janeiro Maru

Depth

9–35 m

Typical dive

23 m average, 50-60 min

Current

Mild to none

Visibility

10–30 m

Water temperature

26–30°C

Entry

Boat / negative entry possible

Level

All levels (Nitrox recommended)

Dive type

Wreck, historical

Night dive

Possible

Region / port

Chuuk Lagoon, Micronesia

Coordinates

7.352, 151.842

Conditions & Currents

Currents within Truk Lagoon, and specifically around the Rio de Janeiro Maru, are generally mild, especially compared to outer reef sites. This sheltered environment makes for relaxed diving experiences, allowing divers ample time to explore the wreck's features and resident marine life without significant exertion. However, visibility can vary from 10 to 30 meters depending on recent weather patterns and sediment disturbance, so being prepared for different conditions is wise. Entry and exit are typically straightforward boat dives, often with negative entries employed to quickly reach the wreck. While strong currents are infrequent, divers should always monitor local conditions and follow guide instructions, especially if planning interior penetrations where unexpected movements could pose a challenge.

Marine life & sighting chances

Hard corals

Year-round · common

Soft corals

Year-round · common

Groupers

Year-round · common

Barracuda

Year-round · common

Reef fish

Year-round · common

Marine turtles

Year-round · occasional

Blacktip reef sharks

Year-round · occasional

Spotted Eagle ray

Year-round · rare

Dive profile & how the dive runs

Your dive on the Rio de Janeiro Maru typically begins with a boat drop directly over the wreck. Given its relatively shallow uppermost point of 9 meters, a controlled descent allows for a gradual acclimation. You will follow the wreck's structure downwards, observing the coral growth and marine life that now call it home. The average depth for exploration is around 23 meters, making it accessible for recreational divers. A key highlight is the exploration of the large engine room, a vast space that can be entered by appropriately certified divers. The dive usually continues along the deck, observing various features and cargo. Turnaround is typically based on air consumption and no-decompression limits, after which you'll slowly ascend, conducting your safety stop along the mast or superstructure before returning to the surface.

Underwater photography

The Rio de Janeiro Maru offers fantastic opportunities for both wide-angle and macro photography. For wide-angle shots, a fisheye or wide-angle rectilinear lens is ideal to capture the immense scale of the wreck, particularly its length and the expansive engine room. Given the varying visibility (10-30m), external strobes are highly recommended to bring out the vibrant colors of the corals and marine life encrusting the metal. For macro enthusiasts, there are numerous smaller inhabitants and intricate coral formations on the wreck. A macro lens will reveal the delicate beauty of nudibranchs, small crabs, and gobies. When photographing inside the wreck, careful buoyancy control is essential to avoid disturbing silt and impacting visibility for yourself and others. Always maintain a respectful distance from artifacts and marine life, and never touch the wreck.

Combine with nearby dive sites

• San Francisco Maru

  A deeper wreck known for its military cargo including tanks and trucks.

• Fujikawa Maru

  A cargo ship featuring incomplete Zero fighter planes in its holds.

• Nippo Maru

  Known for its anti-aircraft gun, howitzers, and a Japanese battle tank.

• Shinkoku Maru

  A tanker that has become a spectacular artificial reef.

Getting there & logistics

Access to Truk Lagoon, also known as Chuuk, is primarily via flights to Chuuk International Airport (TKK). International travelers typically connect through Guam (GUM) or Honolulu (HNL) with United Airlines, with the flight from Guam to Chuuk taking approximately two hours. Once in Chuuk, liveaboards offer the most comprehensive way to dive the many wrecks, including the Rio de Janeiro Maru, with trips typically lasting 7 nights. Land-based dive operations, often based at resorts like Blue Lagoon Resort, also provide daily boat dives to various sites within the lagoon. There are no specific entry fees for the dive sites themselves beyond what is covered by your dive operator. Planning for adequate layovers in Guam is advisable due to potential immigration processing times.

Safety & environment

Diving in Truk Lagoon, especially on wrecks like the Rio de Janeiro Maru, requires adherence to strict safety protocols. The nearest recompression chamber is located in Truk Lagoon itself, though its operational status should always be verified prior to travel. In the event of a serious medical emergency requiring advanced care, evacuation to Guam or beyond would be necessary, a process that can be both time-consuming and expensive. Therefore, comprehensive dive insurance covering emergency medical treatment and evacuation is absolutely essential. Divers should always dive within their certification limits, especially when considering wreck penetration, and only with experienced guides familiar with the site. Given the historical significance, touching or removing artifacts is strictly prohibited to preserve the integrity of the wrecks.

Who it suits, and who it doesn't

FAQ

Rio de Janeiro Maru FAQ

Liveaboards diving Rio de Janeiro Maru

These liveaboards may visit Rio de Janeiro Maru on selected itineraries, the exact dive sites depend on departure, weather and conditions.

Palau Siren

Micronesia

16 guests

Solitude Gaia

Micronesia

18 guests40 m

Palau Aggressor II

Micronesia

18 guests32 m

Black Pearl

Micronesia

24 guests

Ocean Hunter 3

Micronesia

16 guests29 m

Pacific Master

Solomon Islands

20 guests30 m