While I found these personal accounts very moving, in the abstract cruise ship passengers appear considerably safer than their ashore counterparts (although the following does not consider the possibility that incidents might be under-reported).
Annual cruise ship overboard rates are about 1 in a million, compared to about 20 in a million annual drownings across America, suggesting you're 20 times more likely to drown in America than to fall off of a cruise ship.
I can't find an indication of the annual deaths aboard cruise ships, but worst case, if all deaths reported since 1979 had occurred only in the most recent year, that would suggest that Americans in America are about 1,000 times more likely to die than are Americans on cruise liners. But actually those deaths occurred over a period of more than 30 years. Assuming that passenger count and deaths both gradually increased from 1979 to the present, that weakly suggests that maybe Americans in America are something like 20,000 times more likely to die than are Americans on cruise liners.
Using that same approach, worst case, if all deaths reported since 1979 were actually murders and occurred in the most recent year, that would suggest that Americans in America are about 6 times more likely to be murdered than Americans on cruise liners. But cruise liner passengers are much safer than that, because not all reported deaths were murders and those reported deaths occurred across 35 years vice one year.
Data and sources:
The cruise industry has about 20 million passengers a year.
Cruise ships recently reported about 23 annual overboard incidents.
Cruise ships have reported 172 deaths of any cause reported on cruise ships since 1979.
America's annual death rate is 8.39/1,000 (all causes), 4.7/100,000 (murder), and 1/50,000 (drowning) (source:wikipedia)