I had a run-in with the most ferocious dwarf-eating monster I've ever seen in the game. Yes, I've held off forgotten beasts, dragons, hydras, creatures too horrible (or typo'd) to describe!
But this...this was a new horror beyond words. I lost 38 dwarves, 2 caravans; and it ate the better part of 2 goblin sieges.
I speak of course, of the dreaded Dire Waterfall!
I had built my settlement into a mountain side along where two rivers joined into one. One winded through a valley, the other formed a tall tall waterfall and cut a picturesque canyon. For some reason, shortly after my first siege; despite six wells supplied by water in their dining rooms and a plethora of booze, both foreign and domestic; it became the "in" thing to race across the map and try to drink water from a particular square of the waterfall; the last one before the edge, of course!
Invariably, this lead to the dwarf being pushed over the edge, and falling to a horrible drowning death. Imagine my horror as I saw a near continuous line of dwarves; some carrying their infants, racing to try some of that fresh mountain waterfall water!
Burrows, designated drinking areas, strict adherence to zones; no sir! Nothing was going to keep these dwarves from getting a drink or dying trying...well, all died trying. Before this silly internet fad could empty my fortress, I managed to lock my dwarves and that seemed to break the cycle. I sent builders to wall off the waterfall. I lost 6 builders as they'd go try to drink after placing their stones, but it was enough. I left a door on the far side locked.
Like clockwork, the trolls smash that door and the goblins all run to that same square; pitching them off to their deaths. So I guess it's not all bad. I'm in the middle of engineering a way to get to the sweet sweet supply of bodies and loot at the base of the waterfall.
Besides fortress-killing waterfalls; this has been one of the most vicious monsters I've encountered yet.
Easily on par with the Dread Gazeebo...