The answer to this question depends on your itinerary.
The best way to avoid having to worry about pirate attacks is to skip cruises that take you through the Red Sea, Gulf of Aden, North Indian Ocean, the Malacca Straits, or the South China Sea. Many of these voyages are so-called "repositioning cruises" that are used to move cruise ships from one body of water to another. Unfortunately, Somali pirates have not only hijacked cargo ships but also pursued passenger liners, according to the International Chamber of Commerce's International Maritime Bureau Piracy Reporting Centre. The pirates' objectives are to steal passengers' valuables and demand ransom for the safe return of hostages. In recent years, the pirates have focused primarily on merchant vessels and fishing boats, thanks to the anti-piracy efforts of the international maritime community, but the threat to cruise ships has declined, not disappeared.
The US State Department's International Maritime Piracy and Armed Robbery at Sea Fact Sheet includes the following warning:
Two notable sub-sets of maritime crime are armed robbery at sea, occurring within a nation’s territorial waters, and piracy, which takes places in international waters. Both have occurred throughout the world with notable recent concentrations in the waters off Southeast Asia, the Horn of Africa, South America, and the Gulf of Guinea. U.S. citizens considering travel by sea should always exercise caution, especially when near and within areas with recent incidents of maritime crime.
The warning also mentions possible hijackings of merchant vessels and tells US travelers planning to take a cruise that travels through the areas mentioned above to contact their cruise lines to find out which anti-hijacking measures have been put in place to protect passengers.
Although an international naval force is patrolling these waters, the area involved is quite large and it is easy for the naval patrols to miss small pirate vessels.
The International Maritime Bureau Piracy Reporting Centre states that piracy has declined overall, including near the Horn of Africa, Gulf of Guinea, and Malacca Straits, but says that pirate attacks in Philippine waters have increased. In February 2018, NYA reported that pirates are still targeting merchant ships and container ships in the Gulf of Guinea. Passenger ships were not attacked in the Gulf of Guinea between August 2017 and January 2018, according to NYA. Perhaps this is due to the fact that cargo vessels have fewer crew members than do passenger ships.
In addition to the piracy and robbery in the areas named above, the US State Department's International Maritime Piracy and Armed Robbery at Sea Fact Sheet mentions pirate attacks and robbery at sea off the coast of Venezuela, but, as of this writing, these attacks appear to be aimed at general cargo vessels and small yachts.
How to Minimize the Your Risk
With so many cruise itineraries to choose from, avoiding pirate-infested waters is a simple process. All you have to do is select an itinerary that is far away from areas where acts of piracy have occurred. Evidence suggests that pirates are moving farther out into international waters, so paying attention to news of pirate attacks will help you choose a safe itinerary.
Although various media outlets have suggested that ISIS might take to piracy in the Mediterranean Sea, the self-styled Islamic State has not yet committed an act of piracy against a cruise ship. Cruise lines tend to avoid places where terrorist attacks have occurred, but you should still check your proposed itinerary to see whether you will sail through waters known for pirate attacks before booking a cruise.
If you must travel through the Red Sea, Gulf of Aden, Gulf of Guinea, or the North Indian Ocean, take every precaution. Leave jewelry, cash, and valuables at home. Make copies of your passport and other important travel documents. Keep one copy with you and leave a second set with a relative or trusted friend at home. Be sure to register your trip with your Department of State or Foreign Office. Carry a list of emergency contact numbers, including the numbers of your local embassies and consulates, with you. Be sure your family and friends know your itinerary so they can advocate for you if your cruise ship is attacked by pirates.