The Shinyo (震洋, Shin'yō, "Sea Quake") were Japanese suicide motorboats developed during World War II.

Towards the end of 1943, in response to unfavorable progress in the war, the Japanese high command heard suggestions for various suicide craft.

They were typically equipped with a bow-mounted charge of up to 300 kg (660 lb) of explosives that could be detonated by either impact or from a manual switch in the driver's area.

Although the chances of the boat and crew surviving the wave from the explosion might seem slim, a small number of crewmen successfully escaped.

[4] Around 400 boats were transported to Okinawa and Formosa, and the rest were stored on the coast of Japan for the ultimate defense against the expected invasion of the Home islands.