Heian Maru is a huge Chuuk Lagoon wreck with broad passageways, a bridge, an engine room, and cargo spaces that reward multiple dives. Coral growth and reef life soften the steel and make the wreck feel like a layered underwater maze rather than a quick pass-through. The scale of the ship, and the mix of open decks and enclosed spaces, makes it a better fit for slow, deliberate wreck planning than for a rushed sightseeing run.