The amphibious component of Canada's commando organization (Joint Task Force 2, or JTF2) have been practicing dealing with hijacked and ships and cargo ships. It is believed that al Qaeda has plans to seize offshore oil rigs and ships carrying dangerous chemicals (including gasoline or Liquid Natural Gas) and turn them into terrorist weapons. 

JTF2 has, since 1993, been in charge of hostage rescue and counter-terrorism. The unit has seen action in the Balkans and Afghanistan. But recently, elements of JTF2 have been looking into ways to retake hijacked ships and oil platforms. It is believed that terrorists plan to seize ships carrying dangerous cargoes, run them into ports and cause the cargoes to explode. The hijacking could take place as the ship was about to enter a port, thus making military action risky (bombing a ship carrying a dangerous cargo could cause a damaging explosion or chemical spill). Seizing an offshore oil rig would allow the terrorists to cause a major oil spill, and then blow up the rig, causing a large fire as well. Preventing, or mitigating, terrorist attacks like this requires commandos who can come in quietly, quickly and effectively to kill or capture the terrorists before they can do their damage. U.S. Navy SEALs and British SBS (Special Boat Squadron) commandos are also thought to be practicing for similar missions. It's all being kept quite secret, in order to leave the terrorists in the dark about exactly what they might be up against. This is particularly important as the technical details, of how to damage oil platforms or tankers carrying dangerous chemicals, are not well known. The platforms and ships are built to withstand a lot of abuse and are not easily destroyed. So commandos would have some time to get aboard and kill or capture the terrorists.