Azumasan Maru - Iron Bottom Sound

The Azumasan Maru is one of those wrecks we keep coming back to in Iron Bottom Sound. She’s not one of the colossal ones, but her character really shines. Sitting upright, the bow is the shallower end, peaking around 34m, which means you get a good chunk of bottom time if you're mindful of your deco. We always start at the bow, dropping down to that sandy patch to look back at the silhouette; it's a fantastic shot, especially if you catch some schooling fish in the foreground. Our favourite part, though, is the cargo. Head to the second hold, and you'll find a jumble of motorbikes and sidecars. It’s a real snapshot of wartime logistics, frozen in time. Around the wreck, the soft corals have really taken hold, painting the metal in purples and oranges. Look closely, and you’ll spot Hexagon Groupers peeking from crevices, and the flash of Black Butterflyfish against the hull. Visibility averages around 15m, which is decent enough to appreciate the scale and the details, but keep an eye on your depth here; it slopes quickly past the bow. This site really suits divers who appreciate historical context and enjoy a bit of wreck penetration without going too deep or complex.

Location
Iron Bottom Sound, Solomon Islands, Central & South Pacific
Coordinates
-9.351400, 159.845600
Type
wreck

Wreck History - Azumasan Maru

Year Sunk
1942
Vessel Type
cargo ship
Cause
grounding
Tonnage
7,623 GRT

The Azumasan Maru began her life in 1933 as a civilian freighter for Mitsui Bussan Kaisha. With the outbreak of war, she was requisitioned by the Imperial Japanese Navy and converted into a troop transport, a role that would seal her fate in the Solomon Islands. She participated in the initial invasion of Tulagi in May 1942, where she was damaged by aircraft from the USS Yorktown. Her final mission was as part of the 'Tokyo Express,' a convoy desperately trying to resupply Japanese forces on Guadalcanal.

On October 15, 1942, while unloading troops and supplies near Tassafaronga Point, the convoy came under relentless attack from US aircraft based at the nearby Henderson Field. Severely damaged by dive bombers, the Azumasan Maru's captain deliberately beached her to prevent sinking and salvage her precious cargo. She was hit again by B-17 bombers the next day, ensuring she would never sail again. Today, she is a spectacular technical dive, sitting upright on a steep slope that drops into the depths of the legendary Iron Bottom Sound. The bow rests around 40-50 meters, while the stern plummets to over 80 meters. The wreck is adorned with vibrant soft corals and is a world-class site for underwater photographers, offering a hauntingly beautiful window into a pivotal moment in WWII history.

Marine Protected Area: Komarindi

Best Time to Dive in Iron Bottom Sound

The warmest water temperatures in Iron Bottom Sound occur in January, averaging 30.5°C. The coolest conditions are in December at 30.5°C.

Monthly Water Temperatures

  • January: 30.5°C (air: 26.9°C)
  • February: 30.5°C (air: 26.7°C)
  • March: 30.5°C (air: 26.7°C)
  • April: 30.5°C (air: 26.8°C)
  • May: 30.5°C (air: 26.9°C)
  • June: 30.5°C (air: 26.5°C)
  • July: 30.5°C (air: 26.5°C)
  • August: 30.5°C (air: 26.3°C)
  • September: 30.5°C (air: 26.5°C)
  • October: 30.5°C (air: 26.7°C)
  • November: 30.5°C (air: 26.7°C)
  • December: 30.5°C (air: 26.9°C)

Nearby Dive Sites in Iron Bottom Sound

Nearest Dive Centres to Azumasan Maru

Marine Life in Iron Bottom Sound

Home to 415 recorded species including 320 reef fish, 29 hard corals, 18 sea snails & nudibranchs, 16 sea cucumbers, 7 seagrass & algae, 5 clams & mussels.

Notable Species

Recommended Packing List for Azumasan Maru

Based on average water temperature of 30.5°C.

  • Shorty or Rashguard - warm 30°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