The Sankisan Maru sank during the second day of Operation Hailstone with its cargo of military vehicles still secured below decks. The top of the mast breaks the surface, making it easy to find, and the wreck sits at 6–40 metres, making part of it accessible even to snorkellers.
The highlight is the forward cargo hold, where two trucks stand parked as if waiting to be unloaded, now completely encrusted in coral. Their tyres have long since rotted, but the frames, cabins, and wheel housings are perfectly preserved under the growth. Small reef sharks shelter under the trucks. The aft hold contained a mix of supplies and equipment; the vessel also carried ammunition that is now strictly off-limits. The coral coverage along the deck and hull is dense, and the relatively shallow depth means good natural light for photography even without a torch.