Sinpo-class

The Sinpo-class, also known as the Gorae ("whale") or Pongdae class, is an experimental ballistic missile submarine built in North Korea. First observed in 2014 at the Sinpo South Shipyard, it was at the time the largest submarine designed and built for the Korean People's Navy. Only one boat exists, the 8.24 Yongung ("August 24 Hero"), named after the date of North Korea's first successful submarine-launched ballistic missile test.

The design is estimated at around 67 meters in length with a submerged displacement between 1,650 and 2,000 tons, powered by diesel-electric propulsion. Analysts believe the design draws on older Yugoslav submarine types as well as North Korea's experience with Romeo-class boats. Its defining feature is a launch tube in the sail for one or two Pukguksong-1 (KN-11) ballistic missiles.

The 8.24 Yongung carried out North Korea's first successful SLBM launch on 24 August 2016, sending a KN-11 about 500 km into the Sea of Japan during joint US-South Korean exercises. In October 2021 it launched a smaller SLBM identified as the Hwasong-11S, and in March 2023 it was used to fire two cruise missiles during a drill.

The class served as a stepping stone to larger designs. Its successor, the Sinpo-C, emerged in 2023 as the Hero Kim Kun Ok, a heavily modified Romeo-class hull with ten vertical launch tubes described by Pyongyang as a "tactical nuclear attack submarine", though Western analysts assessed it as still not operational two years after its unveiling.