South Korea has launched the second Seo Hui (SS-088) diesel-electric submarine of the KSS-III Batch-II project.
The Republic of Korea Navy and the Defense Acquisition Program Administration (DAPA) announced this.
The ceremony took place on November 3, at the Hanwha Ocean shipbuilder in Okpo, Geoje City.
The Seo Hui is the second submarine in the upgraded KSS-III Batch-II series, following the lead vessel, Jang Yeong-sil (SS-087), which was launched in October 2025.
Construction of the Seo Hui began in 2021 following the signing of the contract, and its keel was laid in 2024.
Seo Hui (SS-088) submarine specifications
- Type: Diesel-electric submarine.
- Project: KSS-III Batch-II (Jang Bogo-III Batch-II).
- Manufacturer: Hanwha Ocean, South Korea.
- Displacement: approximately 3,600 tonnes.
- Length: approximately 89 metres.
- Propulsion system: diesel-electric with an air-independent propulsion (AIP) unit.
- Armament: torpedoes, naval mines, cruise and ballistic missiles.
The new submarine has a displacement 600 tonnes greater than that of the previous Batch-I series.
The enlarged hull has made it possible to increase the capacity for carrying weapons and onboard equipment. In particular, the new series features an increased number of vertical launch systems — ten instead of six on the Batch-I submarines. They are designed to launch ballistic and cruise missiles.
One of the key upgrades was the integration of South Korean lithium-ion batteries.
The Seo Hui’s survivability has been enhanced by installing an auxiliary propulsion system, which allows it to manoeuvre if the main one fails. The submarine is also equipped with a conventional optical periscope, providing direct observation capabilities in the event of an electro-optical sensor failure.
A total of 70 types of South Korean equipment have been installed on the submarine. According to Naval News, this is 12 more than on the first-series KSS-III submarines.
According to DAPA officials, increasing the share of domestically produced components is expected to simplify future maintenance and strengthen the competitiveness of South Korean submarines on the international market.
Following the completion of sea trials, the Seo Hui is planned to be handed over to the Republic of Korea Navy in 2028. It will then undergo preparations for commissioning into active service.
The KSS-III Programme
KSS-III is a South Korean programme to develop large, domestically designed diesel-electric submarines intended to engage surface and underwater targets and carry out missile strikes.
The first submarine in the programme, Dosan Ahn Chang-ho (SS-083), was commissioned into the South Korean Navy in August 2021.
A key feature of the programme is the use of vertical launch systems, which enable the deployment of submarine-launched ballistic missiles.
During the October 2025 launch ceremony for the first Batch-II submarine, Jang Yeong-sil, canisters for the prospective Haeseong-5 supersonic anti-ship missile were also showcased.
Source: Militayni
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