Somali pirates have seized the Maersk Alabama, a US-operated container ship with 21 American crew members aboard. It is the latest in a spate of recent high-profile attacks:
The Malaspina Castle, a UK-owned and Italian-operated carrier, was seized in the Gulf of Aden this week.
Bow Asir, a Norwegian tanker, was captured by pirates off Somalia last month. All 24 crew are still being held and are reported to be well.
The Titan, a Greek-owned cargo ship, was seized off Somalia last month en route to Korea from the Black Sea. The ship and its 24 crew are still being held.
The MV Faina, a Ukrainian ship carrying arms and tanks, was released for a reported $3.2m (£2.2m) ransom in February after being held for almost five months.
The Saldanha, a Maltese-registered cargo ship, is being held with 22 crew on board after being seized in February.
The Sirius Star became the subject of the world's biggest hijacking when it was taken 450 miles out to sea in November carrying about $100m worth of oil. The ship and its 25-member crew, including two Britons, were freed in January after a reported ransom payment of $3m.
The Longchamp, a German-owned tanker carrying liquefied petroleum gas and a crew of 13, is being held after it was seized in January.
The Delight, a Hong Kong cargo vessel carrying wheat, was hijacked in the Gulf of Aden in November.
The Stolt Strength, a chemical tanker with a crew of 23 Filipinos aboard, is being held by pirates after being captured in November.