Okay... so this thread is mostly just me posting... I guess.
Again, you've talked about a course of action, but you haven't really done something.
Even if I wanted to advance based on spoken material, I don't know what you mean by "cautiously".
"Cautiously" could mean: taking the pre'caution' to make sure that the ant doesn't get away by running after it at full speed (x4 run); advancing at move action speed, and the only real 'caution' being that you don't speed up; moving at half speed to use the Perception houserule to maintain a 'high alert' status of 'caution', likely to watch for hazards, traps, and being wary of crude ambushes.
Was all he said as he shined his lantern in the direction of the passage-way the ant went down.
It was barely noticeable to Graal, at the edge of his low-light vision from the hooded lantern of Thror's. So it is as Quill said, but @120ft when seen by Spades, but then it got further away.
I was already using the hooded lantern as the basis of distance, so there is no further information.
Inna?