More common when online such as realms but also occurs in single player. When disembarking from a boat, occasionally the player will be stuck on top of the boat while the boat is invisible as if not there. the player is stuck as if constantly falling because the boat is "not there." the player must then log out and back into the world to make the boat reappear and be able to move again. Also, When the player disembarks while on land often the player will fall through the block below the boat. In cases of nether ice tunnels, the players can fall through into pits of lava.