Chuuk (Truk) Lagoon in the Federated States of Micronesia is widely regarded as the greatest wreck-diving destination on Earth: a sheltered lagoon holding the Imperial Japanese Navy fleet sunk by the US carrier raid Operation Hailstone in February 1944, with more than 40 ships and hundreds of aircraft now resting as a coral-encrusted, legally protected war grave.
Destination info
Conditions, highlights, and the resident marine life.
Conditions
Water and air temperature across the year.
WaterAirDryShoulderWet
Description
Truk Lagoon, today officially Chuuk Lagoon, is a vast atoll lagoon roughly 64 km across enclosed by a barrier reef in the central Caroline Islands of the Federated States of Micronesia. During World War II it served as the Imperial Japanese Navy's principal forward anchorage in the Central Pacific, often called 'the Gibraltar of the Pacific.' On 17–18 February 1944 US Navy Task Force 58 launched Operation Hailstone, a two-day air and surface assault that sank more than 40 Japanese ships and destroyed roughly 250–270 aircraft — the largest single shipping loss of the Pacific war. The sunken fleet, much of it cargo and supply vessels still laden with tanks, trucks, aircraft, munitions, fuel drums and personal artifacts, now lies on the lagoon floor at depths from about 10 m to beyond 60 m, with superstructures cloaked in hard and soft coral, sponges and anemones. The wrecks are protected under Chuukese, Federated States and US law and are treated as war graves — many still contain human remains, so all artifacts and remains must be left undisturbed ('take only pictures'). Conditions are warm and calm year-round inside the sheltered lagoon, with water 27–30°C and visibility typically 15–30 m. Many of the most famous wrecks are deep and require penetration, decompression and advanced or technical training; honest self-assessment of certification level is essential here. Diving is from day boats out of Weno (the state capital) or from dedicated wreck liveaboards.
Highlights
What makes this dive worth the trip.
On 17–18 February 1944 the US Navy launched Operation Hailstone, a two-day carrier raid by Task Force 58 against Truk Lagoon, the Imperial Japanese Navy's main Central Pacific anchorage. It sank more than 40 Japanese ships — over 200,000 tons of shipping — and destroyed an estimated 250–270 aircraft, the heaviest single shipping loss inflicted in the Pacific theatre.
More than 60 wrecks — ships, submarines and aircraft — now rest on the lagoon floor, many of them transport and supply vessels still loaded with their wartime cargo: light tanks, trucks, fighter aircraft, artillery shells, mines, torpedoes, depth charges and fuel drums sit inside the holds exactly as they sank.
The wrecks are protected under Chuukese, Federated States of Micronesia and US law; the United States has designated the site a National Historic Landmark. Because many wrecks still hold human remains, they are treated as war graves: interfering with a site or removing artifacts is illegal and 'take only pictures, leave only bubbles' is enforced as law, not just etiquette.
Marine life
33 species you’re likely to encounter on a dive here.
Dive sites
8 signature sites at this destination.
Betty Bomber (Mitsubishi G4M)
A Mitsubishi G4M 'Betty' medium bomber that crashed in the shallows near Eten Island while attempting an emergency landing, now resting in only about 15–18 m of sand — one of the few genuinely shallow, beginner-friendly aircraft wrecks in Truk. The fuselage broke on impact and the two engines were thrown roughly 90 m forward toward the island, where they lie separately. The intact cockpit and wing sections sit on the sand, making it a relaxed, well-lit dive often used as a check or final dive.
15–18 mbeginnerDay boatLightVisibility 15–30 m
Shinkoku Maru
A 152 m fleet oiler (her name means 'divine country') that took part in the Pearl Harbor strike force before being sunk at Truk, now sitting upright with the bridge near 12 m and the main deck and seabed around 35–40 m. She is the lagoon's signature 'coral garden' wreck and one of the world's most acclaimed night dives, her decks smothered in soft and hard coral, black coral and carpet anemones with resident anemonefish near the midship blast crater. A field hospital, operating table and bottles remain inside, and lionfish, groupers and barracuda are common.
12–40 mintermediateDay boatLightVisibility 15–30 m
Nippo Maru
A 107 m cargo and water-supply ship resting on her port side, with the shallowest structure near 21 m, the main deck around 30 m and the deepest hold reaching roughly 45–48 m. Her best-known feature is a Type 95 light tank sitting on the deck, accompanied by field artillery (howitzers), trucks, munitions, water tanks and mess gear in the holds. The bridge — with its telegraph, helm and instruments — is largely intact, making this a favourite deeper recreational and technical penetration dive. Reef sharks sometimes cruise the deeper wrecks.
21–48 madvancedDay boatLightVisibility 15–30 m
San Francisco Maru (Million Dollar Wreck)
A 117 m armed cargo ship, the most famous deep wreck in Truk and nicknamed the 'Million Dollar Wreck' for the value of her cargo. She sits upright with the deck around 48–50 m and the seabed near 60 m, placing her firmly in technical territory (decompression, often trimix). Three Type 95 'Ha-Go' light tanks stand on the foredeck behind the bow gun, with a truck chassis and a steamroller nearby; the holds are packed with hemispherical beach mines, aircraft bombs, torpedoes, depth charges, cordite and shell casings — among the most heavily laden wrecks anywhere.
48–63 madvancedLiveaboardLightVisibility 15–30 m
Yamagiri Maru
A 134 m passenger-cargo ship resting on her port side at roughly 15 m at the highest point down to about 34 m at the sand. Her signature feature is Hold No. 5, which is stacked with massive battleship artillery shells — replacement main-gun ammunition for the giant Yamato-class battleships (sources describe the projectiles variously as around 14-inch / 18-inch calibre). A steamroller and construction equipment are also aboard, and a notable diveable bridge and engine room reward penetration. Coral and sponge growth covers the exposed starboard side.
15–34 madvancedDay boatLightVisibility 15–30 m
Kensho Maru
A 116 m passenger-cargo ship sitting upright with the bow around 21 m and the sand near 40 m. She is prized for what many divers call the finest engine room in the lagoon — a large two-bank diesel engine, photogenic and easily accessible — plus an intact bridge with a working-looking telegraph and helm, and a tiled galley with a wood-burning stove and crockery. Five holds carry drums, pumps, welding cylinders and bicycles; the bow gun is colourfully coral-encrusted.
21–40 madvancedDay boatLightVisibility 15–30 m
Fujikawa Maru
A 133 m armed aircraft transport and the most celebrated wreck in the lagoon, sitting upright with the mast and superstructure near 12 m and the seabed around 34 m, well within recreational range. Hold No. 2 famously contains the disassembled fuselages of at least nine Mitsubishi fighters (eight A6M 'Zero' and one rare A5M 'Claude'), alongside spare propellers, belly tanks, wheels, machine guns and shell casings; the bow carries a 6-inch gun. The engine room and 'R-shop' machine workshop are popular penetration routes, and the upper decks are heavily coral-encrusted.
9–34 mintermediateDay boatLightVisibility 15–30 m
Heian Maru
At about 155–163 m the largest wreck in the lagoon, a former passenger liner converted to a submarine tender, lying on her port side with the uppermost hull around 12 m and the seabed near 33–35 m. The ship's name is still legible in both English and kanji on the bow. Her holds and decks hold long Type 95 submarine torpedoes, spare periscopes, shells, china, telephones and radio equipment — a vivid record of her role supplying the IJN submarine force. The sheer scale and shallow upper structure make her an accessible yet immense dive.
12–35 mintermediateDay boatLightVisibility 15–30 m
Where to dive & stay
Local dive centers, resorts, and hotels.
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