How do I make a drowning chamber for Goblins in Dwarf Fortress? Please give ascii art examples of each step of the building process. The goblins are in cages already, so the chamber should include an area for the cages to be dropped off.
1. Choose a suitable location for the drowning chamber. You'll want a place that is close to a water source, but also relatively secure so that goblins cannot escape once they are released from their cages.

2. Design the entrance to the chamber. You can use a drawbridge to create an entrance that can be closed and locked once the goblins are inside. You can also build a tunnel leading to the chamber to keep the goblins isolated.

3. Build a holding area for the cages. This area should be secure and isolated from the rest of your fortress. You can use walls, doors, or other obstacles to ensure that the goblins cannot escape from their cages.

4. Create a pit for the goblins to fall into. This pit should be deep enough that the goblins cannot climb out, but not so deep that they die on impact. A depth of 3-4 tiles should be sufficient.

5. Install a floodgate or other mechanism to release water into the pit. You can connect the floodgate to a lever or pressure plate so that you can control when the water is released.

6. Test the drowning chamber to make sure it works. Drop some test subjects (animals or prisoners) into the pit and activate the floodgate to see if they drown.

7. Once the drowning chamber is operational, it's time to use it on your goblin captives. Move their cages to the holding area and release them into the pit. Activate the floodgate to fill the pit with water and watch as the goblins drown.

Remember to monitor the drowning chamber regularly to ensure that it is working properly and that there are no blockages or other issues that could prevent the goblins from drowning. Good luck!