In honor of the Tres Pescadores‘ some-would-say-heroic fight to survive during nine months adrift at sea, we’re taking a gander at another cause of bizarre oceanic disasters (besides “running out of gas and getting lost,” as the Pescadores phenomenon is known) — rogue waves. (Thanks to Damn Interesting for the link.) Historically thought of as little more than tall tales and the stuff of fantastical sea shanties, reports of rogue waves are being taken more seriously these days, and are thought to be responsible for at least a handful of ship sinkings every year. And what frightening sinkings they must be:

• While normal waves in rough seas can measure up to 15 meters in height, rogue waves can exceed 30 meters.
• One account describes the appearance of a giant wave trough which onlookers likened to a “hole in the sea”, followed by a twelve-story-tall “wall of water.”
• Most modern merchant vessels are designed to withstand about fifteen tons of pressure per square meter, but these unusual waves exert a pressure of about one hundred tons per square meter.
• Curiously, rogue waves are often seen traveling against the prevailing current and wave directions; and unlike a tsunami, rogue waves are localized and very short-lived.
• Once regarded as extremely rare, satellite photos and radar imagery have documented the existence of numerous rogue waves, and it turns out that they are far more common than previously thought.

So what causes rogue waves? According to this article, “one theory under investigation cites ‘constructive interference,’ which is a result of several smaller waves overlapping in phase, combining to produce one massive wave.” But that’s just one theory; nobody knows for sure.