Fukuryu Suicide Diver

The Fukuryu (伏龍, "Crouching Dragon") were combat divers trained for anti-invasion suicide operations against Allied landing craft. The diving equipment was developed at the Navy's Engineering School (海軍工作学校) at Yokosuka from March 1945, with a prototype completed in about a month; training began at Yokosuka in mid-1945.

Equipment consisted of a rubberized diving suit with helmet fixed by four bolts, 9 kg of lead weights for ballast, and two 3.5-liter bottles of compressed oxygen at 150 bar; sources give the endurance variously as about five hours or up to ten. Divers were expected to walk along the seabed at a depth of 5-7 meters.

Each Fukuryu diver was armed with a Type 5 attack mine containing 15 kg of high explosives mounted on a 5-meter bamboo pole. Walking submerged, the diver would wait for an enemy landing craft to pass overhead, then push the contact-fuzed mine upward against the hull, detonating it — and inevitably killing themselves in the explosion.

Training was conducted primarily at Yokosuka (71st Arashi Unit), Kure (81st Arashi Unit), and Kawatana near Sasebo. By the end of the war, about 1,200 men had completed training according to English-language accounts, while Japanese accounts state that nearly 3,000 received some training; plans called for 6,000 to be deployed against the anticipated Allied invasion. None of the planned ten thousand Type 5 mines had been completed, only dummy mines for training.

Training itself proved deadly: a number of trainees died from malfunctions in the crude breathing apparatus. The Fukuryu were never deployed in combat before Japan's surrender.