...Create a structure coming out of the waterfall where you can throw the unsuspecting kittens into the "pit/pond"
Or goblins. Or elves.
Sorry to inject near pointless newb questions into this fun thread, but I have to: I have a fort with a less-cool but similar river canyon. Are you saying there's a way I can designate a square *out in open space* where people can drop unwanted elves items from adjacent squares to feed to the carp way down below?
Yup. Use the 'i' zone designation command to designate a zone that has at least one space where a dwarf can stand next to an open space. I'm not sure if your zone also has to include the open space, but I alway do so. Once you've designated the zone, hit 'p' to make it a pit. Then any time you want, you can use 'i' again to select your pit zone, then hit 'P' and you'll get a list of animals/caged prisoners. Select the one(s) you want dropped in.
I've had trouble getting animals dropped if they don't start out in a cage. I can't seem to get my dwarves to just go grab a loose animal and pit it. They'll grab a loose animal and take it to the butcher's, though. <shrug>
You can have your dwarves take a goblin from a cage and lead him to the pit and drop him. I've read that thieves will often escape when being led to a pit, so I haven't tried it with them. I've had no problem with goblin soldiers, though. They will docilely follow a dwarf to their doom. I guess the dwarf grabs them by the ear and drags them along.
"Oh! leggo my ear! that hurts! ow! oh! where are you taking me? Ow! Ok, I'm coming! Ow! hey, that's a long way down there ow! hey! wait! i don't! Ahhhhhhhhhhhhhhhhhhhhhhh! <splat>"