Dive Site: Heian Maru

About Heian Maru

The Heian Maru, a former Japanese passenger-cargo vessel, rests upright in Chuuk Lagoon, making it a pivotal dive site for those exploring the rich history of Operation Hailstone. Sunk during the intense aerial assault in February 1944, this 155-meter ship is the largest remaining wreck in the lagoon. Its immense scale and diverse internal structures, including a prominent bridge, spacious engine room, and cargo holds, offer an unparalleled exploration experience over multiple dives. The wreck's hull begins at a depth of 12 meters, extending down to its deepest point at 36 meters, allowing both recreational and more experienced wreck divers to explore its various sections. The Heian Maru lies in sheltered lagoon waters, characterized by minimal currents, which enhances the safety and enjoyment of penetration dives into its broad passageways. Visibility typically ranges around 20 meters, though it can fluctuate with weather conditions and specific locations within the lagoon. Despite its wartime origins, the Heian Maru is now a thriving artificial reef. Healthy coral growth, sponges, and sea fans have colonized its steel structure, creating a habitat for a variety of marine life. Divers frequently encounter grey reef sharks, groupers, jackfish, lionfish, and snappers navigating the wreck’s nooks and crannies. The transformation from a military transport to a vibrant ecosystem underscores the unique blend of history and natural beauty found in Chuuk Lagoon. Diving the Heian Maru is a deliberate experience, best approached with careful planning rather than a hurried tour. Its layered environment encourages divers to return repeatedly to uncover new details and discover its hidden marine inhabitants. As with all wrecks in Chuuk, it is considered a war grave, necessitating a respectful approach to its exploration.

Dive site facts: Heian Maru

Depth

10–36 m

Current

Very little

Visibility

20 m

Water temperature

28–30°C

Entry

Boat

Level

Intermediate

Dive type

Deep Wreck

Region / port

Chuuk Lagoon, Micronesia

Coordinates

7.37, 151.828

Conditions & Currents

The Heian Maru is situated within the sheltered waters of Chuuk Lagoon, which typically experiences very little current, making it ideal for wreck penetration. While the lagoon generally offers calm conditions, visibility around 20 meters can vary depending on weather patterns and specific areas of the lagoon. Divers should expect minimal surge, enhancing the stability for exploring the wreck's many features. These mild conditions mean entry and exit are usually straightforward, but awareness of potential silt disruption inside the wreck and surrounding areas is crucial for maintaining good visibility, especially during longer penetrations.

Marine life & sighting chances

Grey Reef Shark

occasional

Grouper

common

Basslet

common

Jackfish

common

Lionfish

common

Snapper

common

Nudibranch

common

Crustacean

common

Anemone

common

Dive profile & how the dive runs

Diving the Heian Maru typically begins with a boat drop directly onto the wreck, which lies in minimal current. You can descend to the hull at approximately 12 meters, allowing for a gradual exploration. The main route often involves exploring the expansive bridge, before moving into the broad passageways and cargo holds that house historical artifacts. Divers can navigate through various decks, observing the transformation of the vessel into an artificial reef. A popular path involves moving deeper towards the engine room, reaching depths of around 36 meters. Due to its size and numerous features, multiple dives are recommended to fully appreciate the wreck. The safety stop is generally conducted in the shallower sections of the wreck or near the mooring line, allowing for continued observation of marine life congregating on the upper decks.

Underwater photography

The Heian Maru presents excellent opportunities for both wide-angle and macro photography. For capturing the sheer scale of the wreck, its expansive decks, and the penetration opportunities into the bridge and cargo holds, a wide-angle lens is essential. Natural light penetrates well to the shallower sections, but for deeper areas and internal shots, external strobes or powerful video lights are highly recommended to illuminate details and bring out the vibrant colors of soft corals. Macro photographers will find a wealth of subjects among the intricate coral growth, nudibranchs, and crustaceans that have colonized the wreck. Pay close attention to your buoyancy, especially within the interior, to avoid silting and ensure clear shots.

Combine with nearby dive sites

• Fujikawa Maru

  A Chuuk Lagoon wreck dive known for aircraft relics and extensive coral growth.

• San Francisco Maru

  A deep cargo wreck in Chuuk, often considered a technical dive due to its depth.

• Shinkoku Maru

  A coral-covered tanker wreck that rests upright in Chuuk Lagoon.

• Nippo Maru

  A large supply vessel offering diverse cargo and marine life.

Getting there & logistics

Access to Chuuk Lagoon and the Heian Maru primarily involves international flights to Guam, followed by connecting flights to Weno, Chuuk. Liveaboards are the most practical way to experience the numerous wrecks in the lagoon, offering itineraries that typically range from 7 to 10 days. These vessels provide direct access to multiple dive sites, including the Heian Maru, within a single trip. Shore-based options are also available, with dive centers operating from Weno. There are generally no specific dive permits for the Heian Maru beyond the standard Chuuk Lagoon diving fees, which are usually included in liveaboard or dive package costs. Booking several months in advance is advisable due to the popularity of this destination.

Safety & environment

Diving the Heian Maru, like all wrecks in Chuuk Lagoon, requires a strong emphasis on safety. Divers should be aware of the overhead environment, especially during penetrations, and exercise caution to avoid sharp edges, entanglement hazards, and disturbing silt. Advanced Open Water and Wreck Diver certifications are strongly recommended for exploring deeper or interior sections. All wrecks in Chuuk are considered war graves, so divers must treat them with respect and adhere to local site rules and guide instructions. The nearest recompression chamber is located in Weno, though evacuation from remote dive sites to the chamber can take time. Comprehensive dive insurance, including coverage for medical emergencies and evacuation, is highly advisable for all divers.

Who it suits — and who it doesn't

FAQ

Heian Maru FAQ

Liveaboards diving Heian Maru

These liveaboards may visit Heian Maru on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Palau Siren

Micronesia

16 guests

$501/day

Solitude Gaia

Micronesia

18 guests40 m

$310/day

Palau Aggressor II

Micronesia

18 guests32 m

$360/day

Black Pearl

Micronesia

24 guests

$390/day

Ocean Hunter 3

Micronesia

16 guests29 m

$350/day

Pacific Master

Solomon Islands

20 guests30 m

$268/day