AIKOKU MARU - Chuuk (Truk) Lagoon

The Aikoku Maru is one of those wrecks that just hits different. We love that it’s a big ship, nearly 150 metres long, sitting upright and mostly intact on the seabed at 55 metres. Descending through the blue, you start to make out the superstructure, then the sheer scale of the hull. It’s dark down there, proper deep wreck diving, so good lights are essential. Our favourite part has to be the cargo holds, especially Hold No. 3, where you can still see stacks of ammunition and even skeletal remains - a sobering reminder of its history. Another highlight is the stern, where the massive propeller is still in place, encrusted with thick sponges and hard corals. Schools of barracuda often circle the mast, and we’ve seen plenty of reef sharks cruising by. While it’s a deep dive, the lack of strong current and generally good visibility in Chuuk means experienced wreck divers will find it a truly rewarding exploration. Just remember your bottom time and plan your deco stops properly.

Location
Chuuk (Truk) Lagoon, Micronesia, Central & South Pacific
Coordinates
7.374167, 151.917220
Type
wreck
Maximum Depth
55m

Wreck History - AIKOKU MARU

Year Sunk
1944
Vessel Type
ammunition ship
Cause
combat
Tonnage
10,437 GRT

The Aikoku Maru was a modern Japanese vessel that began her career in 1940 as an armed merchant cruiser, raiding Allied shipping lanes. She was later converted to a submarine tender and finally to an ammunition and troop transport ship, a role that would seal her fate. As part of the Japanese fleet stationed at the formidable naval base in Chuuk (Truk) Lagoon, she was a key logistical asset for the Imperial Japanese Navy's operations in the Pacific.

Her end came on February 17, 1944, during the massive US Navy air raid known as Operation Hailstone. While attempting to escape the lagoon, the Aikoku Maru was struck by an aerial torpedo from a US Navy Avenger. The torpedo detonated in a hold packed with ammunition, triggering a catastrophic explosion that vaporized the forward section of the ship and sent her to the bottom in seconds, taking hundreds of embarked soldiers with her. The blast was so powerful it was reported to have downed the attacking aircraft.

Today, the Aikoku Maru is one of Chuuk Lagoon's most famous deep wrecks, resting at a depth of 55 meters. The 150-meter-long vessel is a somber and awe-inspiring sight. Divers can explore the relatively intact stern, complete with large anti-aircraft guns, before moving towards the shattered bow section that serves as a testament to the violence of her sinking. It remains a powerful underwater memorial to those who perished in the attack.

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)

Nearby Dive Sites in Chuuk (Truk) Lagoon

Nearest Dive Centres to AIKOKU 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

Recommended Packing List for AIKOKU 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