South Korea’s fifth KSS-III submarine floated out

Other features include noise-reduction technology, auxiliary propulsion to preserve manoeuvrability if the main propulsion system fails, and a hull-penetrating periscope for observing directly when electro-optical sensors are impaired.

The submarine is named after Seo Hui, a statesman of the Goryeo Dynasty.

Steel cutting for Seo Hui took place on December 30, 2021, and her keel was laid in 2024. She follows the lead Batch-II boat, the future ROKS Jang Yeong-sil, which was launched at Geoje on October 22, 2025 and is due for delivery at the end of 2027.

The third KSS-III Batch-II submarine is scheduled for delivery in 2031.