How do lock staircases help boats travel through hilly areas?

Lock staircases help boats navigate hilly terrain by functioning as a series of connected, isolable basins that allow vessels to ascend or descend significant changes in elevation.1

In a waterway, the route is often divided into level steps known as pounds. When a boat encounters a change in height that is too great for a single lock, a staircase—a sequence of these basins—is used to manage the transition. By filling or emptying each individual chamber in the sequence, the water level is adjusted incrementally, enabling the vessel to move safely from one pound to the next. This system effectively breaks down a large vertical rise into manageable stages, allowing for navigation through areas where the landscape would otherwise be impassable.21