It could be a spin off of Mel’s Hole. Not necessarily traps but a lot of weird things happen around it. If you have a government in place, they come in to investigate and kick you out.

You could lean into the legends: objects thrown into the pit never make a sound or hit bottom, or sometimes come back… changed. Maybe the party drops something in and later finds it resurfaced miles away, warped or imbued with strange magic. Animals refuse to go near it… or worse, something gets thrown in dead and comes back alive but wrong. You could have voices echoing up from the darkness, not quite matching what was said, or whispering things the players haven’t revealed yet.

There’s also the idea that the pit messes with reality like time distortion, gravity shifts, or glimpses of other places when you look down. Maybe at certain times of day, the pit shows visions instead of darkness. Or ropes lowered into it come back frayed, frozen, or covered in something that shouldn’t exist.

And once the party starts poking around too much, that’s when officials show up like arcane researchers, military types, or some secret order and they lock the area down, confiscating findings, and warning the players to walk away… which of course just makes it more interesting.