Maybe it is time to stop dancing around this idea:
I know the first time I was on a cruise ship it struck me how easily someone could disappear if they fell over. It is like looking over a very steep crevice where you cannot see the bottom due to overgrowth, etc. The thought just occurs to you because we are all wired to understand things like that on a very basic brain level.
Inevitably, the sight of fast moving water below a cruise ship is just going to stimulate certain thoughts in certain people pre-disposed to those kinds of thoughts - specifically suicidal.
The truth is, if I knew someone who had recently tried suicide and was still in a fragile state, I would not recommend they go on a cruise. It is a little like recommending they walk across the Golden Gate bridge.
People do commit suicide during cruises. Statistically I do not know if it is any more per 100,000 than is statictically normal, but I wouldn't be surprised - because of that thought we all get when we look over the side of a cruise ship.
Now, to a normal person that would never be a reason not to cruise. That would be like saying one shouldn't go to the Grand Canyon to see its beauty because people commit suicide there.
No HERE IS SOMETHING IRONIC. Before I wrote that I googled "Grand Canyon Suicides" just to see how common it is and 33 people committed suicide in U.S. National parks in 2008 alone.
They call it "Death by Canyon" and that makes it 5-times more prevalent than suicide by cruise ship.
And DavidB, it isn't politically correct to mock people who are suicidal. It is a mental condition related to depression, not a malicious intent.