Sōryū-class submarine

The Sōryū-class submarines (16SS) are diesel-electric submarines that entered service with the Japan Maritime Self-Defense Force in 2009. The design is an evolution of the Oyashio class submarine, from which it can most easily be distinguished by its X-shaped tail planes. The Sōryūs have the largest displacement of any submarine used by post war Japan.

The class are fitted with air-independent propulsion based on Kockums Stirling engines license-built by Kawasaki Heavy Industries, allowing them to stay submerged for longer periods of time.

Naming convention
Japanese submarines since World War II were named after ocean currents. The JMSDF changed its naming convention with the Sōryū and submarines will now be named after mythological creatures. Sōryū (そうりゅう) means blue dragon in Japanese and is named after the World War II carrier sunk during the Battle of Midway.

Exports
Japan may offer Sōryū-class submarines to Australia to replace the Royal Australian Navy's Collins class submarines.