I built a setup to test a bug my friend sent to me. See screenshots for the structure I made.

I found that if you fall into the void while in a boat, you become a "ghost" entity, where you cannot manipulate anything, including mobs, blocks, and toggleable blocks like levers and doors. You are invincible in this state, even in survival mode, and mobs will not notice you.

Your character will look like he/she is still in the boat when you have done this correctly.

I will attach the world file. To pull this bug off you must first turn on the water via lever, place a boat on the sign, turn the water off, and get into the boat.

After you begin to fall, look at the boat and wait for it to disappear. Once it is gone, fly back up and you are now a ghost entity.