Hoistedlens saw three more goblin sieges in quick succession. Normally nothing too bad, but the third claimed a ton of dwarves anyway because when I temporarily drained the reservoir to set up a pump stack (and coincidentally also allowing my dwarves to claim the dozen-odd corpses of dwarves that had tried to drink from the flooding room when I was setting it up... This resulted in the pacification of something like six ghost babies.) half my dwarves decided to simultaneously become thirsty, ignore warrens settings, and march out to the brook en masse. And one of my legendary miners decided to try a spot of fishing on the opposite side of the map. The siege ate them, of course. Eventually I covered the goblins in lava.
Before that I was attacked by a glacier titan: A blob of steam with a broad shell and an austere look. It assaulted my legendary metalworker (who later died in the same siege that claimed my miners and those other dwarves) and ineffectually pushed him for a few days. He, on the other hand, just took a nap and ignored it, then finally got fed up and shot it. I got a message that he was 'caught in a burst of steam!' but even that didn't actually harm him. Oh well. Free glacier titan shell!
Oh, and I finally reached the second cavern layer on this map. This layer, unlike the first one, actually has life in it! I could hypothetically cut down the mushrooms from in there if I could actually reach any of them - this particular cavern is very... vertical.