Western Intelligence services have long asserted that Al-Qaeda has an ambitious maritime capabilities program. Reportedly, operatives have received swimming and scuba training for demolitions and suicide attacks. Al Qaeda is also reported to own or control an estimated two dozen merchant ships world-wide, and is generally believed to make heavy use of dhows and other small vessels to move personnel, resources, and equipment around in Middle Eastern waters. In addition, it is believed that al Qaeda has trained personnel in small boat operations, for both individual attacks, such as the one that crippled the USS Cole, and in swarm  (many, even a dozen or more, boats) attacks, with rumors that they have even conducted training in the United States.

So why haven't we seen much evidence of al Qaeda activity at sea? Certainly there are more than enough targets. Large numbers of American, NATO, and coalition warships are active in Middle Eastern waters, supporting operations in Afghanistan, Iraq, and all across the Arabian Sea and adjacent areas, waters also frequented by large numbers of tankers and other commercial vessels. Nevertheless, since large scale operations began in the region in late-2001, in Afghanistan, there appears to have been only one attack on a commercial vessel, against a French tanker off Yemen over two years ago. And four years of intensive MIO (Maritime Intercept Operations) in the region  has managed to intercept only a handful of suspect vessels and personnel, with little evidence of any ties to al Qaeda. It is, of course, possible that the high density of the coalition maritime presence has had a serious deterrent effect on al Qaeda's maritime operations. But al Qaeda has shown itself to be rather immune to deterrence in other situations. Given the movement's track record, one could reasonably expect that they would deliberately set up a situation in which a MIO turned into a disaster, when the intercepted vessel blew itself and the boarding party up. But this has never happened, despite thousands of opportunities. 

Have al Qaeda's maritime resources have been seriously over-estimated, or have Coalition maritime security measures seriously impeded their employment, or are they holding back for some future operations? Its unclear, but at the moment, al Qaedas naval threat is more theoretical than real.