When sailing in an ocean, I went to third person mode to see more around me. Field of Vision was still normal. My boat hit a squid, and I fell out. I sunk to get my sticks, and when I was swimming up, I noticed an odd box around my feet.

Steps to Reproduce:

1. Press F5 once
2. Jump into an ocean (deep enough that there is at least 10 blocks of water under you)
3. Look upwards, so you can see the sky.
4. Move around your mouse, since you can only see the box from certain angles.

– Apologies if this is a duplicate. I did several searches pertaining to boxes underwater, but only found glitches involving hit boxes.