A ship's captain taken hostage by Somali pirates managed to jump into the sea on Friday night, but was recaptured.
The escape attempt by Captain Richard Phillips was witnessed by a United States navy ship nearby, but happened too fast for it to come to his aid.
The 17,000-tonne Maersk Alabama freighter was hijacked on Wednesday, 645km offshore.
Pirates seized the ship but the crew initially fought them off. Captain Phillips was being held on a lifeboat after he apparently volunteered to be a hostage for the sake of his crew.
Captain Phillips managed to leap overboard but the pirates jumped in after him and hauled him back on board.
It is the first time Somali pirates have captured an American. They reportedly want $US2 million for his release.
According to the East African Seafarers' Assistance Programme in Kenya, pirates are currently holding 18 vessels with a total of 267 hostages.
A second US warship, the USS Halyburton, has arrived off the Somali coast. A US destroyer, the USS Bainbridge, is already there.
Somali pirates have released a owned tanker, MT Bow Asir after receiving a ransom payment from the Norwegian owners.
The Salhus Shipping AS confirmed on Friday that the vessel was freed and the 27-member crew was unharmed. Sources put the payment at around $US2.4 million.
The ship was captured on 26 March about 250 miles offshore.