Oh, that's very clear in the article. I did like the fact that the cruise ship had high-power hoses and 'ghetto blasters' (in the James Bond sense!) to help fend them off. I remember seeing something on one of the science channels about sound as a weapon, and didn't realize it had made it into civilian hands already.
That said, the idea of going out to see what's going on wouldn't cross my mind even once. Captain says get down, he's not telling you to make like John Travolta on a Saturday night.