Heian Maru

At over 150 m, the Heian Maru is the largest ship in the lagoon — a prewar NYK passenger liner converted into a submarine tender, caught at anchor in the February 1944 raids. Her name remains readable on the bow in both Latin and Japanese characters, a detail that stops most divers mid-fin-kick. Because she rests on her side, swimming her length feels like flying along a steel cliff: propellers, promenade windows, and holds where spare periscopes and torpedo bodies lie racked in the dark. Her scale means most visitors take two dives to feel they have seen her at all.

その瞬間のために: The lettered bow; periscopes and torpedoes in the holds; the sheer scale of a liner-sized hull on its side.

地形: Hull on its port side across the lagoon floor at about 34 m

エントリー: Moored dive; orientation matters — the ship lies on her port side, so decks read as walls.

危険生物・リスク: Sideways orientation disorients inside; long swim distances for the air supply; torpedo warheads and ordnance remain in the holds.

保全: Widely treated as a war grave — crew died in the attacks. Dive her as a memorial: nothing lifted, nothing rearranged, remains untouched.

ナイトロックス: ここでは効果的です——このエリアのプロファイルは、ナイトロックスが無減圧潜水時間を有意に延ばせる水深帯にあります（適切なトレーニングを受けていることが前提です）。