Attack submarines for the Philippine Navy: What to know

Manila: South Korea has offered to sell the Philippine Navy two submarines based on its KSS-III design, customised as the “KSS-III PN” variant for the Philippines.

This marks a major step in Manila’s aspiration to acquire undersea warfare capability, a move seen as vital to bolstering the country’s defence.

These submarines measure approximately 89.4 meters in length with a 9.7-metre beam and displace about 4,000 tonnes when submerged. 

They are powered by a modern diesel-electric propulsion system equipped with lithium-ion batteries and air-independent propulsion (AIP) technology, which allows extended underwater endurance and quieter operation compared to older battery or traditional systems.

Crew, weapons system

South Korea's KSS-III submarine variant currently in service has a crew of 50, displaces 3,358 tonnes surfaced and 3,705 tonnes submerged and measures 274 feet long with a 31.5-foot beam.

The submarines offered to the Philippines feature up to 10 vertical launch cells in addition to six 533mm torpedo tubes.

Their advanced systems include long-range sonar, modern combat capabilities, and stealth features suitable for Philippines' maritime defense needs.

Recently, Philippine President Ferdinand Marcos Jr had a bilateral meeting with South Korean President Lee Jae Myung on the sidelines of the 32nd Asia-Pacific Economic Cooperation Leaders’ Meeting in Gyeongju on October 31, 2025.

Executives of South Korean shipbuilder Hanwha Ocean also discussed with President Marcos the proposal to assist the Navy's submarine programme.

Deal, delivery details

The proposed deal includes not just the submarines but also a comprehensive package involving submarine base construction, maintenance, repair and overhaul (MRO) facilities, crew training, technology transfer, and logistical support. 

Hanwha Ocean, the South Korean firm offering this, presented the package to Philippine officials with plans for a submarine base possibly in Subic Bay or a location chosen by the Philippine Navy.

Delivery is estimated to occur within seven years after the contract signing. 

The total cost for two submarines and the associated support package is projected between 80 to 110 billion Philippine pesos (approximately $1.3 billion to $1.9 billion), aligned with the Philippine Navy’s budget for this key modernisation effort, as per the Inquirer.

This acquisition represents the Philippines’ first-ever submarine procurement, marking a significant enhancement of its naval capabilities with one of the most advanced diesel-electric submarine classes available in the region.

Fact File: KSS-III PN Submarines for Philippines

• Length: ~89.4 meters

• Beam: 9.7 meters

• Displacement: ~4,000 tons submerged

• Propulsion: Diesel-electric with lithium-ion batteries, AIP technology

• Launch Cells: Up to 10 vertical launch cells

• Torpedo Tubes: 6 x 533mm tubes

• Technology: Advanced sonar, combat management system

• Cost: 80-110 billion PHP (~$1.3-$1.9 billion)

• Delivery: Estimated within 7 years

• Additional: Includes base building, training, MRO, tech transfer