Every October, plenty of otherwise sensible adults pay good money to be scared. We hang fake cobwebs on the porch, let masked teenagers chase us through corn mazes, and line up for yet another sequel about a villain who should have stayed dead years ago. We love a good fright, as long as it isn't real. The trouble is that this year's most persuasive horror story isn't playing at the multiplex. It is unfolding, with a kind of patient indifference, out in the open ocean, in wat