I was then told by another player that they had a cave north of our location, they had not gone in it but they had established a camp near it.
Later, while exploring for fish, we found out they had died to a boar attack on their last player. I then proceeded to go into the cave near there. After much roaming around, this is what I realized...

The cave entrance is 1 unit too far away from the cave terrain to actually be used, and the cave's wall are able to be "Mined".
Is this iteration of a cave a terrain generator error, or an example of the new update's fun risks?
In other words, bug or not bug.
Edit: I forgot to mention, yes, you can enter, but not leave.