SS Rakuyo Maru (楽洋丸) was a passenger cargo ship built in 1921 by the Mitsubishi Shipbuilding & Engineering Company, Nagasaki for Nippon Yusen Kisen Kaisha.

Serving as a troopship in World War II, the Rakuyō Maru was torpedoed and sunk by USS Sealion on 12 September 1944.

The Japanese survivors of the Rakuyō Maru were rescued by an escort vessel, leaving the POWs in the water with rafts and some abandoned boats.

A total of 1,159 POWs died, including Australian rugby union player Winston Ide and Brigadier Arthur Varley.

The dead included 350 POWs who were bombarded in lifeboats and killed by a Japanese navy vessel the next day when they were rowing towards land.