After exiting a boat some times, you will be able to break blocks, but no items will drop. upon reloading, you will be in an empty space where you slowly sink until you are sitting on top of the void. No commands work and you can't move around. the pause menu and F3 still work and you can look around, just the world is broken or corrupted.
this has only ooccured once, and the world is still broken/ unusable. I was getting out of a boat in a deep ocean biome, into a swamp biome.