Truk Lagoon holds the world's greatest concentration of accessible WWII shipwrecks. More than 40 Japanese vessels were sunk here in February 1944 during Operation Hailstone, and they remain on the seabed almost exactly as they went down — their holds still carrying tanks, aircraft, trucks, torpedoes, and the mundane cargo of a fleet that never knew the attack was coming.
The wrecks range from the Fujikawa Maru, a 6,000-ton cargo ship at 18–34 metres with Zero fighters in its hold, to the massive Shinkoku Maru, a tanker whose engine room is still intact and whose decks have been colonised by enormous gorgonian fans and schools of barracuda. The Sankisan Maru is famous for the row of trucks still parked in its hold, now coated in soft coral. Hard corals, black coral trees, and sea fans in vivid orange and purple make almost every wreck photogenic even in murky conditions.
Most wrecks are suitable for recreational divers at 15–40 metres, though some go deeper. A handful require technical certification. Dive operators based at Weno (Moen) island run daily trips; liveaboard boats allow multiple dives a day and access to outer reef sites. Night diving is particularly atmospheric — giant trevally hunt across the wrecks, and the water glows with bioluminescence.