Last week, I got bored with my 5 year old fortress, and opened the floodgates to my moat, which were strategically positioned to lead to a channel in the bottom level of my fortress. Some of the dwarves locked themselves in their rooms and survived for a little while longer than the ones who ran about the halls, drowning in waves which crashed through those hallowed, statue-lined halls. They ended up dying of starvation anyway, though. Those who locked themselves in the food cellars survived only slightly longer, but after being forced to watch so many friends decay, a couple went completely berserk and slaughtered the rest.
I wish you could have scuba gear in adventure mode.