Aka Island Suicide Attack Boat Bunker
This is one of two bunkers that concealed suicide attack boats on Aka Island; another two were on Geruma Island. The boats in this particular bunker belonged to the Second Sea Raiding Squadron. Equipped with rails and with the capacity to store five boats, it was excavated by a construction battalion made up of island residents and Korean laborers.
The suicide attack boats were made of plywood and powered by automobile engines. Weighing 1,200 kilograms, they were 5.6 meters long and 1.8 meters wide, and were designed to be driven by a solo pilot whose mission was to crash with his payload of two 120-kilogram depth charges into a US naval vessel. The boats were known as Maru-Re, a name derived from the first syllable of renrakusen (liaison boat) written inside a circle (maru in Japanese).
The Japanese army had high hopes for this “secret weapon,” which had proved quite effective during the Philippines campaign, and had 100 suicide boats concealed in the bunkers on the islands of Aka and Geruma and a further 100 on Zamami Island. These hopes were not fulfilled. Contemporary Japanese records describe the boats being “destroyed in air raids or blown up by our own side, with not even one managing to make a sortie.” In some cases, the bunkers collapsed on top of the boats or the boats suffered a direct hit that rendered them unusable; in other cases, the boats’ launch site was destroyed.