The supply ships present at Truk Lagoon during Operation Hailstone in 1944 were in the process of loading and unloading their supplies. With the world at war, a lot of these supplies were munitions big and small. The photo above shows one of the front holds of the Sankisan Maru with thousands of bullets piled up. Diving over the piles of lead is a strange experience – these bullets never got to their intended destinations and now sit peacefully on the bottom of a tropical blue ocean.
These massive shells are quick fire ammunition in brass casings. From the other end it’s easy to see that they’re still loaded and ready so go, despite being underwater for 70 years. I saw these on my second day of diving at Truk and thought they were pretty large. But of course there’s always something bigger around the corner. These are torpedo bodies:
The Gosei Maru was a submarine tender now sitting on her side in the shallows. These massive torpedo bodies lie in her aft holds, partially spilled out onto the sand. The torpedoes were capable of 20 miles of underwater travel to reach a target. They contained both fuel and compressed air or oxygen. As the bodies rusted through over the decades underwater there have been periodic explosions of the gas tanks within. I can imagine that even a small bang would make me quite nervous while swimming past this much unexploded ordnance, and these torpedo bodies seem unlikely to produce small noises.
The torpedoes come with contra-rotating propellors on the back, designed to increase torque across a smaller blade radius. On the opposite side of this hold we could see stacks of torpedo batteries spilling out of their casings. If the bullets are too small and the torpedoes too big, hold number 5 of the Yamagiri Maru has these artillery shells. Supposedly 14 inch shells, they are over a metre long and designed to go in the main armament guns of battleships. They’re a popular photographic subject and with a bit of daylight coming in to help with lighting I can see why.
The Yamagiri was damaged by a US submarine in 1943 and ended up at Truk Lagoon for repairs. She was still being repaired when Operation Hailstone started in February 1944 and was directly hit by three bombs. The third one started a fire on board and she sunk quickly. If she had stayed afloat much longer there might not have been much of her left once the fire got to this cargo.