Frankly I'm surprised it doesn't happen more often. I've often wondered how long before some cruise ship plows ashore (ok, this wasn't ashore), what with all the ferried ramming into their moorings we've had lately.
Cruise ships are mass graves, defying death on a quirk of physics. That anyone is calm on one blows my mind - don't they know even in the best of circumstances, they're bobbing precariously above 2 miles of cold, black liquid funeral full of lovecraftian horrors?