[15][16] The 1,200 tonne ship started sinking at 21:20 local time (12:20 UTC) about 1 nautical mile (1.9 km) off the south-west coast of Baengnyeong Island in the Yellow Sea.

Cheonan's captain, Commander Choi Won-il, said that the ship broke into two and the stern sank within five minutes after the explosion and while he was still assessing the situation.

[26] On 30 March 2010 it was reported that one South Korean naval diver (ROKN UDT/SEAL CWO Han Ju-ho) had died after losing consciousness whilst searching for survivors and another had been hospitalised.

[28] On 15 April 2010, the stern section of the ship was winched from the seabed by a large floating crane, drained of water and placed on a barge for transportation to the Pyongtaek navy base.

[31] The salvaged parts of the ship were taken to Pyongtaek navy base for an investigation into the cause of the sinking by both South Korean and foreign experts.

[32] On 20 May 2010, a South Korean-led international commission investigating the sinking of Cheonan presented its findings, stating that the ship was sunk by a North Korean torpedo attack.

[9][33] The torpedo parts recovered at the site of the explosion by a dredging ship on 15 May, which include 5x5 bladed contra-rotating propellers, propulsion motor and a steering section, were claimed to perfectly match the schematics of the CHT-02D torpedo included in introductory brochures provided to foreign countries by North Korea for export purposes.

1 in English), found inside the end of the propulsion section were said to have been consistent with markings on a previously obtained North Korean torpedo.

[34] However, an expert at a South Korean missile manufacturer disagreed with the idea that the submarine alleged by ROK authorities to have shot the torpedo actually has the capability: "Sango class submarines are known to be used by North Korean commandos in infiltrating areas or laying mines, but they apparently do not have an advanced system to guide homing weapons.

"[36] One member of the investigative team, Shin Sang-cheol, who would be summoned on charges of spreading unsubstantiated rumors, publicly expressed doubts by saying "The magnified photo of the evidence showed that the marking was written on the rusted surface.

"[38] On 13 September 2010, the final report was issued by JIG which concluded that, "The Cheonan was split and sunk due to a shockwave and bubble effect generated by the underwater explosion of a torpedo.