You suppose you can't deny "down" as an option until you try it.

Subconsciously, you feel like you already know what the texture of the ground(?) beneath you is from having walked on it. You still opt to kneel down and try touching it regardless, and you're not so much disappointed as you are even more confused than before. The floor seems entirely absent of texture. There is just a barrier of nothing that's keeping you in this position. The most you can call it is flat and smooth, but it is entirely devoid of characteristics otherwise.

You stand back up and begin to consider a different option.