I'M loving TIRED OF IT! HOW!? HOW!?
I have a mine that I made myself with no nooks/crannys and is 100% lit up. I block the entrance whenever i go in/leave so there's 100% no chance of enemy spawning apart from slimes which haven't spawned so i'm assuming they're not in my chunk but for the 4th loving time I have come down there to almost be killed by a creeper. The only thing saving me is the fact that the straight hallways make it impossible for him the sneak up on me.
Also, my boat has disappeared twice and I was only 6 metres away from it both times so it couldn't of despawned. MY ISLAND IS HAUNTED HELP.
Theory:
Herobrine(How did you guess) is stealing my boats and placing mob spawners(He can do that cos he is a descendant from the people who made dungeons. That's my guess) and trying to freak me out.
Likely actual reason:
Stuff happens in the game when if you go away from somewhere underground mobs like to appear.