Seikan Ferry Wartime Disaster Site (Tsugaru Strait)

The Seikan Ferry Wartime Disaster Site (青函連絡船戦時遭難地) marks the waters of the Tsugaru Strait and Hakodate Bay where, on July 14-15, 1945, US Navy carrier-based aircraft annihilated the Seikan ferry fleet — Japan's sole rail-sea link between Hokkaido and Honshu.

On the morning of July 14, over 50 Grumman fighter-bombers from Task Force 38's fast carrier strike force launched their first wave at approximately 5:00 AM, targeting ferries underway in the strait and at anchor in both Hakodate and Aomori harbors. Attacks continued in waves until the afternoon. A second day of strikes on July 15 finished off the remaining vessels. The toll was catastrophic: the Dai-4 Seikan Maru sank at 6:18 AM southeast of Cape Kattoshi; the Matsumae Maru ran aground and burned at Nanae Beach at 7:20 AM; the Dai-10 and Dai-3 Seikan Maru went down at 7:30 AM; the Tsugaru Maru sank at 3:10 PM east of Cape Kitsunegoshi; the Dai-2 Seikan Maru and Hiran Maru sank off Aomori harbor at 3:30 and 3:40 PM respectively; and the Shoho Maru followed at 3:55 PM. The Dai-1 Seikan Maru was sunk on July 15. Of the 12 ferries in service, 10 were sunk or burned and the remaining 2 were heavily damaged.

The human cost was devastating — 352 people died on July 14 alone, and the total number of crew members and passengers killed is given as 424, making this one of the worst maritime disasters in Japanese home waters during the war. Among the ships lost, the Tsugaru Maru, the Dai-3 Seikan Maru, and the Dai-4 Seikan Maru went down in the open waters of the Tsugaru Strait.

The strategic impact was enormous. The Seikan ferries were the sole means of transporting Hokkaido's coal — Japan's most critical remaining energy resource — to Honshu's war industries. With the fleet destroyed, coal shipments to Honshu fell sharply, dealing a crippling blow to Japan's already faltering industrial output in the final weeks of the war. It is often described as one of the most strategically effective air attacks of the Pacific War.

The principal memorial, the Cenotaph for the Seikan Ferry War Disaster (青函連絡船戦災の碑), was erected on July 14, 2005 at Aomori Port beside the preserved memorial ship Hakkoda Maru (八甲田丸). A separate cenotaph for fallen crew members stands on the slopes of Mount Hakodate. The memorial ship Mashu Maru at Hakodate Port also contains exhibits documenting the wartime destruction of the ferry fleet.