Exploring the Heian Maru Wreck: A Journey Through Truk Lagoon’s Largest Shipwreck

Truk Lagoon, located in the Federated States of Micronesia, is one of the most iconic wreck diving destinations in the world. Among the many remnants of World War II’s Operation Hailstone resting beneath its waters lies the Heian Maru, the largest shipwreck in the lagoon. At over 500 feet long, the Heian Maru offers a fascinating dive experience for history buffs and underwater explorers alike, providing a glimpse into both the past and the thriving marine life that now calls the wreck home.

In this article, we’ll take an in-depth look at the Heian Maru’s history, what divers can expect when exploring the wreck, and why this site has become a must-see attraction for those visiting Truk Lagoon.

1. The History of the Heian Maru: From Passenger Liner to Submarine Tender

The story of the Heian Maru begins long before it became a famous wreck. Launched in 1930, the ship was originally built as a passenger liner, operating between Japan and the United States. The Heian Maru was part of the NYK Line, a prestigious shipping company, and was known for its luxury and efficiency.

However, with the outbreak of World War II, the ship’s role changed dramatically. In 1941, the Japanese Imperial Navy repurposed the Heian Maru as a submarine tender, tasked with supporting and supplying Japan’s growing fleet of submarines. The ship was outfitted with equipment, spare parts, and munitions to assist submarines in battle.

By 1944, as the tides of war turned against Japan, Truk Lagoon became a critical base for the Japanese military. The Heian Maru, stationed in the lagoon, was actively supporting submarine operations when Operation Hailstone struck. On February 17, 1944, the U.S. Navy launched a massive air raid on Truk, targeting the ships and military infrastructure within the lagoon. The Heian Maru was hit during the attack and eventually sank, taking with it the war supplies and equipment it carried.

Today, the wreck sits on its port side at a depth of approximately 33-35 meters (110-115 feet), a lasting reminder of the war’s impact and the region’s historical significance.

2. Diving the Heian Maru: A Massive Wreck to Explore

At 163 meters (over 530 feet) in length, the Heian Maru is Truk Lagoon’s largest wreck, making it a captivating site for divers. The sheer size of the wreck means there’s plenty to explore, and it often takes multiple dives to fully appreciate all its features.

• The Bow and Forward Hold: The bow of the Heian Maru is one of the first things divers will encounter, and it’s an impressive sight. The forward hold is filled with submarine periscopes, torpedoes, and other equipment that was used to service submarines during the war. These artifacts give divers a unique look into the ship’s role and its wartime operations.
• The Bridge and Superstructure: Moving toward the midsection, divers can explore the ship’s bridge and superstructure. Although much of the bridge has collapsed over the years, it still offers interesting areas to navigate. The large superstructure is encrusted with corals and is home to a variety of marine life.
• Torpedo Storage: One of the most iconic sections of the Heian Maru is its torpedo storage. Divers can see rows of torpedoes that were never used in combat, now resting peacefully on the seafloor. This part of the wreck adds to the historical significance of the dive, offering a glimpse into the weaponry that played a crucial role in the Pacific theater of WWII.
• The Engine Room: For more advanced divers, the Heian Maru’s engine room is an exciting place to explore. The ship’s massive engines are still largely intact, although overgrown with marine life. This area requires careful navigation, as it’s easy to get disoriented in the maze of machinery and tight spaces.

3. Marine Life on the Heian Maru: A Thriving Artificial Reef

While the Heian Maru serves as a historical monument to a bygone era, it has also become a thriving artificial reef, home to a diverse array of marine species. The wreck is covered in soft corals, sponges, and sea fans, creating a vibrant and colorful underwater landscape.

• Fish Species: Schools of fish such as trevallies, snappers, and groupers are commonly seen around the wreck. Divers often spot jacks patrolling the area, along with smaller reef fish like butterflyfish and angelfish darting in and out of the corals.
• Macro Life: The Heian Maru is also a favorite site for macro photography. Tiny critters like nudibranchs, shrimps, and crabs can be found in the crevices of the ship, providing excellent opportunities for underwater photographers looking to capture unique shots.
• Larger Marine Life: It’s not uncommon to see larger species such as reef sharks and eagle rays cruising around the wreck. The lagoon’s nutrient-rich waters support a wide range of marine life, making each dive on the Heian Maru a different experience.

4. For Divers of All Levels

One of the great aspects of the Heian Maru wreck is that it can be enjoyed by divers of varying skill levels. While certain sections of the wreck, such as the engine room, are better suited for advanced divers due to tight spaces and depth, much of the ship can be explored by recreational divers.

• Shallow Sections: The wreck’s shallowest parts sit at around 15-18 meters (50-60 feet), making it accessible to less experienced divers. The bow and some of the upper sections of the ship provide plenty to see without requiring deep penetration or advanced technical skills.
• Advanced Exploration: For more experienced divers, the deeper sections of the wreck offer opportunities to explore areas such as the cargo holds, the engine room, and the torpedo storage. These areas require careful planning and navigation, but the rewards are worth it, providing a deeper understanding of the ship’s history and layout.

Whether you’re a beginner or an advanced wreck diver, the Heian Maru has something to offer. The combination of historical artifacts and marine life creates a dive experience that is both educational and awe-inspiring.

5. Preserving History Beneath the Waves

Diving the Heian Maru is not just about exploring a wreck; it’s about experiencing a piece of history. The wrecks of Truk Lagoon, including the Heian Maru, are considered underwater museums, each telling a story of the Pacific War. Preserving these wrecks is crucial, as they serve as historical artifacts that help future generations understand the impact of WWII on this region.

Divers are encouraged to respect these sites, avoid disturbing the wreck or its surrounding marine life, and take only photographs and memories with them. Many dive operators in Truk Lagoon emphasize the importance of responsible diving, ensuring that these underwater treasures remain intact for future explorers.

Final Thoughts

The Heian Maru wreck is one of the most iconic and largest shipwrecks in Truk Lagoon, offering an unforgettable experience for wreck divers and history enthusiasts alike. Its combination of historical significance, fascinating underwater artifacts, and vibrant marine life make it a must-visit dive site for anyone traveling to Truk Lagoon.

Whether you’re exploring the shallow sections of the ship or diving deep into the holds and engine room, the Heian Maru offers a unique journey through history. As you swim alongside torpedoes and periscopes, surrounded by schools of fish and colorful corals, it’s easy to forget that you’re diving in one of the most significant battle sites of WWII.

For those seeking both adventure and a connection to the past, the Heian Maru delivers an experience like no other, making it a standout destination in the vast underwater landscape of Truk Lagoon.