The difference between simple piracy and maritime terrorism is the motivation for the crime - monetary or political, respectively. This book goes into why terrorists do not try to hijack oil tankers or blow up cruise liners. The effects they want to achieve are quite simply on the land more often than not, and the sea has a series of complications.
Learning how to successfully navigate the ocean is in itself a career, and the skills of a terrorist do not translate well to the great blue. Training in maritime abilities costs a lot of money that terrorist networks would rather spend on more useful programs. Last but not least, it is extremely easy to foil terrorist plots at sea, as they can literally be seen from a mile away.
Sure, some maniac might try to drive a speedboat into the side of a cruise liner strapped with 100kg of plastic explosive, but with the multiple-hull systems that are currently in use, it most likely won't do much. The entire book is simply an explanation of why this won't work, but also notes that we mustn't underestimate the creativity of these people. Decent read.
5/10