Falkirk Wheel, Scotland, United Kingdom

The docking-pit is a drydock-like port which is isolated from the lower canal basin by means of watertight gates and kept dry by means of water pumps. When the wheel rotates and stops with its arms in the vertical position it is possible for boats to enter and exit the lower caisson when the gates are open without flooding the docking-pit. The space below the caisson is empty.
If it were not for inclusion of the docking-pit the caissons and extremities of the arms of the wheel would be immersed in water at the lower canal basin each time the wheel rotates. This would result in a number of undesirable situations developing, such as providing buoyancy to the bottom caisson and the viscosity of the water causing an increase in the required power.
How the canal was routed through the wheel
The route chosen to take the Union Canal to the site of the wheel involved building a completely new section of canal, leading from the original terminus at Port Maxwell to link up with a new basin to the south of the wheel.