>Dive Destinations>Chuuk

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• Diving season
• Where is it?
• Reef summary
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...Highlights: great macro life/ marine diversity, schooling fish & big pelagics...
...Diving environment: wreck diving, advanced divers, off the beaten track...

Officially known as Chuuk, Truk is an island group state in Micronesia, composed of several atolls and islands, with a barrier reef that contains coconut palm-filled beaches fringing a diverse marine seascape. The largest, Truk Lagoon, is considered by many experts to be the best recreational wreck diving destination in the world. Chuuk was a strategic military base for Japan during World War II and the target for the US Operation Hailstone in February 1944 which led to the sinking of over 50 shipwrecks with cargos consisting of tanks, bicycles, trucks, aeroplanes, mines, bombs, and machine gun bullets.

Besides being known for so many shipwrecks and pristine reefs, a beautiful tropical climate and fantastic beaches, it is located near the Coral Triangle - the world's center of marine bio-diversity. The large number of wrecks within such a small area, and the superb variety of fish, corals, and other sea creatures, attract a large number of dive tourists that are eager to explore by liveaboard a remote destination in pristine condition.

The lagoon’s dive sites are accessible to every level of scuba diver. There are many shallow wrecks to dive at, as well as options for exploring deep inside the structures of various wrecks, where you will be captivated by the historic artefacts, and the marine life that has been attracted by the shelter presented by the wrecks. Macro subjects like nudibranchs, crustaceans, and anemones, or even larger animals like reef sharks, are sighted. The dive conditions are superb, with warm water guaranteed all year round and very little current inside the lagoon which makes the diving relatively easy.

Dive Site Descriptions

Operation Hailstorm, launched during World War II, was a pivotal military strike that reshaped the Pacific War theatre, as well as the underwater landscape in Truk Lagoon, now renowned for its world class wreck diving. The operation was initiated by the U.S. Navy in February 1944, targeting the Imperial Japanese Navy's formidable base at Truk, known as the Gibraltar of the Pacific.

This stronghold had long been a key strategic point for the Japanese military, housing fleets, ammunition, and essential war supplies. The U.S., keen on crippling Japan's military strength, saw the base as a critical target. The assault began with a massive air raid, involving hundreds of U.S. aircraft from several carriers in the task force. Over the course of 2 days, American bombers and fighter planes systematically attacked Japanese ships, aircraft, and facilities stationed in the lagoon.

The sheer power of the attack overwhelmed the Japanese forces, sinking more than 40 ships, including battleships, cargo ships, and submarines, as well as destroying nearly 250 aircraft. This devastating blow was a turning point in the Pacific War, effectively neutralizing Truk as a military base.

The aftermath of Operation Hailstorm left a graveyard of sunken ships scattered across the seabed of the lagoon, which over time became one of the world’s most famous dive destinations. The wrecks, preserved in the lagoon’s relatively calm waters, now lie covered in coral and marine life, creating an underwater museum of history. Divers can explore these ghostly relics, including ships still laden with cargo, tanks, and even fighter planes. The vibrant marine ecosystems that have flourished around the wrecks add to the unique and eerie beauty of the dive sites.

Aikoku Maru

This Japanese military transport ship has one of the most tragic stories in the lagoon. The Aikoku Maru was a converted passenger liner used to transport troops and supplies. It was hit by a massive explosion and many soldiers were killed in the attack. The wreck lies in deeper water at a depth of 20-64 meters (65-210 feet) and the bow is heavily damaged from the blast but also surrounded by beautiful coral. Large fish species often lurk here and reef sharks frequently buzz by.

Betty Bomber

At a max depth of 18m/60 ft, lie the remains of a Japanese Mitsubishi G4M plane wreck, known as the Betty Bomber, that crashed into the lagoon in 1944. While not as deep or extensive as the shipwrecks, it offers a fascinating look at the remnants of an aircraft from WWII, with its radio, machine guns, and even a lavatory. The fuselage is still intact so divers can see the cockpit and wings clearly, with many small reef fish, anemones, and coral growth around the wreck.

Fujikawa Maru

This military cargo ship is the one of the most famous and photographed wrecks in Truk, with the maximum depth of 37m/121 ft. The Fujikawa Maru carried planes and other military equipment of the Imperial Japanese Navy, and scuba divers can now explore its holds, where the remains of Mitsubishi Zero fighter planes, spare plane parts (belly tanks, propeller blades, tires and wheels), shell casings, machine guns, gas masks, cooking utensils, beer bottles, fuel drums, and much more are still stored. The ship’s superstructure sits upright and is adorned with colorful corals and anemones with abundant reef fish, including angelfish and butterflyfish, as well as reef sharks and turtles.

Heian Maru

At 150 meters (492 feet) long, the Japanese submarine tender, Heian Maru, is the largest wreck in Truk Lagoon. Its purpose was to carrying torpedoes, deck guns, and supplies for the Japanese subs during the Pacific War. Located at a depth of only 9-23 meters (30-115 feet), the wreck is shallow enough for easy access, and divers can explore the ship's enormous engine room and scattered torpedoes. Also periscopes, China ceramics, telephones, radio equipment, medical kits, and beer bottles are visible. The wreck attracts large schools of fish, coral growth, and offers a thriving habitat a which marine species like barracuda and jacks can hunt.

Hoki Maru

A large freighter carrying military supplies, the Hoki Maru offers a unique experience because of the heavy equipment, like bulldozers and trucks, still lying in its hold at 21-50 meters (69-165 feet). The wreck was torn apart in the attack, with massive sections still intact and others scattered across the seabed. Diver can explore this coral-encrusted wreck with fish schools, critters, and sea anemones.

I-169 Submarine

The Japanese sub I-169 is the only known submarine wreck in the lagoon. The forward section was blown apart by Japanese depth charges after the submarine was accidentally flooded. The conning tower is mostly complete but lies to the side of the submarine, and the aft section is relatively intact. This is one of the few wrecks in Truk where penetration is not recommended due to the frequent silt outs.

Nippo Maru

The Nippo Maru is an exciting 21-47m (69-154 ft) deep wreck with plenty to see, making it one of the all-time diver favorites in Truk. Scattered over the wreck is a small Japanese battle tank, the remains of trucks, and twin-barrelled anti-aircraft guns. Down in the holds are various types of munition, range finders, mess gear, beer bottles, and water tanks. The spectacular engine room is widely believed to be the first point of contact by enemy torpedoes during Operation Hailstone.⁠⁠ The bridge is probably the best intact example in Truk with the ship’s telegraph and steering binnacle still in remarkable condition. School of barracudas can be sighted here.

Rio de Janeiro Maru

The Rio de Janeiro Maru was a luxury passenger liner that was converted for military use during WWII. It is one of the larger wrecks in Truk Lagoon, offering divers the chance to explore spacious cargo holds that contain hundreds of beer bottles, some still in their cases, the bridge, and even the deck's anti-aircraft guns. At a depth of 9-35 meters (30-115 feet), the wreck is relatively shallow, making it easy to navigate and a good site for scuba divers of all levels.

San Francisco Maru

A Japanese cargo ship, the San Francisco Maru is the one of the deepest wrecks in Truk Lagoon, at about to 50-64 meters (164-210 feet). It is known as the "Million Dollar Wreck" because of the incredible and valuable artifacts still on board. Divers can see tanks, trucks, mines, bombs, and ammunition in the ship's holds. This is a technical dive due to the depth, but it offers an incredible exploration of WWII history, together with some beautiful local marine life and occasional sightings of large pelagic species.

Shinkoku Maru

This large tanker sits in about 12-40 meters (40-130 feet) of water and is one of the most beautiful wrecks in the lagoon, being heavily encrusted with soft corals, sponges, and sea fans. The ship is remarkably intact, and divers can explore the bridge, crew areas, engine room, and infirmary, where medicine bottles and surgical equipment are still visible. Large schools of fish might accompany divers that linger to admire the vibrant coral formations.

Unkai Maru

This craft served as a Japanese cargo vessel (freighter) during the war. Built in 1905, it was initially a merchant ship used for transporting goods, including coal and raw materials, across Japanese trade routes. As the war escalated, the Unkai Maru was requisitioned by the Japanese Navy to support military operations, carrying supplies and ammunition to various outposts in the Pacific.

The wreck now lies at a depth of 18-44m (60-144 ft). It is considered to be the final resting place of Japanese soldiers and seamen since the forward holds contain many personal items including gas masks, shoes, china (with the 5-point blue star insignia of the Imperial Japanese Army), and numerous bottles. The engine room is small but accessible. The aft holds are largely empty, but in the stern are depth charges and an old-fashioned steering quadrant. The original gun maker’s markings on the Unkai’s bow gun are clearly visible, showing that it was manufactured in 1898.

Yamagiri Maru

Sitting at a depth of 15-33 meters (49-108) feet, the Yamagiri Maru is known for the visible damage it sustained during the Operation Hailstone attack, making it one of the more historically significant dives. Another transport ship, it contains massive 14-inch battleship shells in its hold. Divers can enter the engine room and view its large propellers. It is such an incredible spot for seeing spectacular coral formations, reef fish, and even occasional manta rays.

How to Dive Truk

Over 60 wrecks are scattered across a wide region known as Chuuk Lagoon. For easy access to all the remote dive sites, Truk liveaboards provide the most flexibility to enjoy your underwater experience without unnecessary logistical difficulties.

You can choose a regular 1 week or an 8/9 night diving cruise to visit a wide range of sites based on individual experience and interests. Whether you’re a recreational diver or a technical diver, the liveaboards have experienced guides who can customize the diving schedule to ensure you get the most out of your trip.

Being the most famous wreck diving location on the entire planet, it’s always recommended to book several months in advance.

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The Diving Season

The diving season in Truk Lagoon lasts year-round as visibility is fairly consistent, day time temperatures remain between 25.5-30.5°C (78-87°F), and rain is only ever intermittent. There are no notable seasonal marine life events. The dry season does run from December to April. This is the most reliable time for diving in Chuuk as there is less rainfall, lower humidity, and clearer skies. The sea is generally calm, offering better visibility (up to 30-40 meters (100-140 ft) on good days). The water temperature hovers around 28-30°C (82-86°F), making it very comfortable for diving though its disadvantage can be a higher tourist volumes and increased dive traffic.

The rainy season lasts from July to November which brings more frequent tropical storms and heavy rains, especially from January to March when it can rain on most days. However, the rains are often short, with clear skies returning quickly. The water remains warm, but visibility may reduce to 15-20 meters (50-70 ft) due to runoff and increased plankton. Stormy weather can occasionally affect boat trips and dive site access. However, visitor numbers are smaller and dive sites less crowded.

For more on the climate and sea temperature at Weno, Truk Lagoon, visit the Weather Spark.

Where is Chuuk and How Do I Get There?

Review our map below showing Truk's location in the world.

Chuuk is one of the 4 Federated States of Micronesia in the Pacific Ocean, northeast of Papua. It consists of several volcanic island and coral atoll groups, with Yap to the west and Pohnpei to the east. Weno in Chuuk Lagoon is the capital city and home to Chuuk International Airport (TKK). Most flights arrive via Guam (which has USA immigration regulations) from Hong Kong, Manila, Incheon or Tokyo with United Airlines. You can also arrive from Honolulu with United Airlines, via the Marshall Islands.

A permit is not required for any person visiting the for 30 days of less; all visitors will be issued a tourist visa on arrival. Visas are usually issued for 30 days but can be extended once you have arrived. You will need to have a valid passport (minimum 12 months validity from planned date of entry) and a return or onward ticket. You can check the latest entry requirements on the Embassy of the Federated States of Micronesia website.

Reef Summary

Depth: 15m - >40m
Visibility: 15m - 40m
Currents: None to gentle
Surface conditions: Often calm, can be choppy in rainy season
Water temperature: 28°C - 30°C
Experience level: Intermediate - advanced
Number of dive sites: ~60
Recommended length of stay: 8 - 10 days

Useful References

• Chuuk cruise trips