The Iranian Navy’s indigenously-built frigate, IRIS Dena, sank in the early hours of Wednesday, off the southern coast of Sri Lanka. The warship was hit by a US submarine while returning from the International Fleet Review 2026. At least 87 people were killed after the ship was sunk on the Sri Lankan southern coast.
The IRIS Dena was one of Iran’s most modern combatants, a Moudge-class frigate commissioned in June 2021. Built at the Bandar Abbas naval factories, it was a symbol of Iran’s indigenous defence capabilities. Named after Mount Dena, the warship measured about 95 meters in length with a beam of nearly 11.1 metres, and an estimated draught of 3.25 metres. It belonged to the Southern Fleet of the Iranian Navy.
COMBAT ASSETS
The IRIS Dena submarine was equipped with a 76-millimetre DP rapid fire auto-cannon, a Fath 40 millimetre AA cannon, a Bofors copy, and C-802 / Noor surface-to-surface missiles (SSMs). In addition to this, the ship also had two Oerlikon 20 mm canons, two triple 324 millimetre light torpedoes, two crew-served Oerlikon 20 mm canons, two triple 324 millimetre light torpedoes, four Sayyad-2 surface-to-air missiles (SAM), and two Chaff dispensers.
PROPULSION AND PERSONNEL
The warship had two 10,000-hp engines and two 740-hp diesel generators. With a displacement of 1,500 tonnes, it was a modern, conventionally powered, diesel-electric attack submarine, ready to perform defence activities in the coastal area and carry out regional operations.
The ship carried a total of 140 passengers, out of which 87 died after being hit by a US torpedo. Calling it an atrocity at sea, Iran’s Foreign Minister Seyed Abbas Araghchi said that the US would “bitterly regret” the action.
