Minecraft wiki entry for Elevators, associated text: The design allows for a boat (occupied or empty) to be carried along with a rail system. Due to the way tracks function, one can essentially move a boat in the same manner allowing for more flexibility in transportation. Because of the way entities work, a boat in a minecart has infinite momentum. An example would be when two different bodies of water are at different elevations. The design from the above video can transport the player and their boat between the two bodies of water without exiting the boat, creating a type of elevator.