Because it is often the result of failure or laxity in patrolling sea routes, piracy flourished in times of unrest, or when navies ordinarily protecting commerce were engaged in war. Pirates found their most suitable base of operations in an archipelago that offered shelter together with proximity to trade routes.
In modern times ships, as well as aeroplanes, are also hijacked for political reasons. The perpetrators of these acts could be described as pirates (for instance, the French for plane hijacker is pirate de l'air), but in English are usually termed hijackers or terrorists. An example is the hijacking of the Italian civilian passenger ship, the Achille Lauro.