Sometimes, while in a boat in the water and Quiting the game, reloading the game will result in some very unexpected and glitchy behavior.

First off, the boat will be gone and you will be left either sinking into the water or possibly stuck glitching ontop of the invisible entity.

Once you can move, any interactions done within a small radius is all that is saved, and your position will be reset upon reloading the world. You cannot mess with any blocks beyond the radius, and only mobs within can be affected. Any mob in the boat with you will also vanish. Reloading the world multiple times can either do nothing or fix itself with the boat and it's mob gone. Damage done by everything else besides you, including TNT, can damage the world and it saves in that state. Mobs far from the glitch player position will freeze in place.

A video I have made trying to demonstrate this is here:
https://youtu.be/x0XdJtJu9W8

This could be a duplicate of MC-144784 or an extension to. Depends on how it is looked at, I guess.