I have the impression, from this thread, that people take the matter of safety as either being 'a joke' or 'any shudder is a sign that we're sinking'.
I'd be most interested to read the opinions of a true professional who could advise us 'passengers' of just what is and is not something we should think about.
When you count back over the years, whilst there have been many incidents that attract attention, in actual fact, there have been very few (any?) sinkings of cruise ships. ie. Abandon ship - lifeboats. Nevertheless, history tells us that *anything* can happen and the better prepared the ship's crew and passengers are, the less 'cost' to all - in any form.
We need not ponder over films or theoretical mega Tsunamis - we need to be aware of what the ship can and will deliver in terms of passenger protection.
As for 'turning turtle' - only a marine architect can comment - and even then - a whloe lot depends on x y and z.
The bottom line is - attend lifeboat drill - *listen* *think* and be prepared just in case that most unlikely and unlucky event pays you a visit. Just like airline passengers.