When you press shift to exit the boat it will let you above the boat and when you are trying to move left, right ,backwards or forward it will teleport you back to the top of the boat also if you make 17 jumps on it (without any armor) and then making the18th landind on a block (no water nor the boat) it will surelly kills you.

P.S I would like to record it but I dont know how to record so... There wont be any proof but try it .