So I went underground while I was mining and I looked down a little bit and saw that half the room was see through, I couldn't see any caves or anything though when it happened. Also it wasn't because I was in f5 I did it in first person as well and had the same result as you can see in the 3rd screenshot. And the roof was about 8 blocks high. Added 2 more screenshots showing the graphical glitch a little bit better.