There is no mechanical system to this elevator, it's all just water and a giant floating platform. After the elevator reaches the top, they raise a small wall that blocks the water in the elevator from the top level of the pool.

What do you need for a water elevator?

Items You Need to Make a Water Elevator in Minecraft

Are water elevators real?

Canyon Activity Pool area is a labyrinth of nine individual pools across six levels. At 770,000 gallons total, the pools are connected via intertwining slides — and the world's first water elevator. Built in 1991, this water elevator is the only one of its kind in the world.