Suburban airport, now closed, is next to some very low swampy steam bottom.
One evening, I took off for some practice of instrument maneuvers, with a safety pilot.
Returning, the runway was completely obscured for half its length (There is a significant up grade to the north).
We clicked the lights on, they were clearly visible, and I did the normal pattern and landed. The runway ahead mostly disappeared, but the lights remained visible for at least one light, but the center line was not visible over the nose. The depth reduced as we went up the runway, and the runway ahead appeared before the runway to the side did, and we turned off at the midpoint, which was merely fuzzy. My co pilot was observing other directions than I, and commented on the disturbance to the surface as our prop wash and wing lift changed the surface of the "milk" we were landing into.
I guess that the depth of fog at the touchdown point might have been 10 feet. I did not drive home on the road that went down and over the creek!