Minecraft wiki entry for Donkey, associated text: Tamed and saddled donkeys are some of the fastest means of transportation or hauling in the game, although they are unable to fit through single block-wide openings. They can also be used to climb hills and jump fences, which the player can't generally. They can be ridden in water up to 2 blocks deep. In deeper water, donkeys separate from the player and swim uncontrolled.