Aids TO Navigation is the Coast Guard term for placing buoys, daymarkers, lighthouses, LORAN stations and other such items that help ships navigate in tricky waters.
I have no idea if markers had any effect on todays Cruise Ship Calamity, but a good buoy system does help prevent things like striking rocks. (navigation is just as important of course and there is the possibility that the rock was uncharted, either through recent geologic activity or oversight.)
Anyway, here is video of the cruise ship sinking. It is very fortunate that loss of life was so low.