Sometimes dwarves wander down there and people get hurt but it does make things more interesting. I caught a GCS and set up silk farm and also use caged beasts to train my animal trainerm He's almost legendary and I sell any tamed beasts I don't need to caravans as well. You can line all the map edges with traps and pretty much anything that enters will be caught. I also capture a lot of live wildlife in cage traps. A singke barrel for pot can be worth 10000-20000 dwarfbucks. I have lavish meals set to produce constantly and I trade all the excess to caravans which actually becomes quite value. I have a lot of monster hunters in my fort so they are constantly killing things which has given me thousands of meat. Added a drawbridge that I could close in case of a forgotten beast, and two chained war dogs to catch any gremlins that try to enter my fort. What I did was add a long corridor lined with cage traps into the caverns to stop any wildlife from coming in. However just recently I started leaving the caverns open to my fortress and it isn't reallyas bad as I remember. However this caused me to seal up the caverns everytime I found them and never touch them again after that. I don't know how exactly this happened since crundles are such pushovers and usually run away with fear. In one of the first fortresses I've ever built as soon as a I breached the caverns almost immediately after my fortress was swarmed by crundles and pretty much everyone died.

Dwarf fortress cavern description