News background from 12 December 2005 and a PINR questioning the threat from Maritime terrorism:
In October 2000, al-Qaeda carried out an attack on the U.S. Navy destroyer the USS Cole while it was anchored in Aden Harbor in Yemen. Shortly before noon, two suicide bombers approached the USS Cole in an explosive-laden speed boat and detonated it along the port side of the vessel. The blast tore open the Cole's steel hull and killed 17 members of the crew.
Two years later, the MV Limburg was the target. The super-tanker was attacked in the Gulf of Aden as it approached Yemen's Ash Shihr oil terminal. Again, a small boat was used which exploded as it approached the vessel. Despite causing substantial damage to the side of the Limburg, only one crew member was killed in the attack.
In June 2002, Moroccan authorities foiled a number of attempts to attack commercial and naval vessels transiting the Straits of Gibraltar. Following the arrests of several Jemaah Islamiyah (J.I.) operatives in Singapore in 2001, it was revealed that the group has planned to attack visiting U.S. naval warships in the region.
In February 2003, after the arrest and interrogation of al-Qaeda's Abdelrahim al-Nashiri, it emerged that the group had intended to attack ships in the Straits of Hormuz. The planned operation would use a number of small craft, which would be packed with explosives and discharged from a "mother ship" once in position near passing U.S. warships.
By far the most lethal maritime terrorist incident this millennium was the attack on the M/V Superferry 14 in Manila by the Abu Sayyaf Group in February 2004. Just after midnight local time, a bomb exploded onboard the passenger ferry, which had left Manila Bay two hours earlier. The resulting fire caused the ship to capsize, and more than 100 people were killed in the attack.