In some rivers or canals the water is not too deep for large ocean-going ships. In such places large watertight compartments are built that help ships and boats go up or down different levels on rivers or canals. These are called canal locks.
In certain areas, man-made canals are constructed to connect two water bodies. These canals are built to help cut down the distance a large ship would otherwise have to take to reach its destination. The canals are therefore constructed at a higher level, like the Panama Canal to prevent land on either side from getting flooded.
The canal is divided into various levels according to its depth. The compartment or lock in which the ship enters is very large and rectangular with gates on each end. A ship that needs to go to a higher level enters the bottom or downstream gate. The gates are then closed.
Once the ship enters the lock, water is pumped in by means of sluices (holes) in the gates. The water level in the compartment is then raised to that of the higher level and the upstream gate is opened for the ship to get out to the next level.
At each level, water is pumped in or emptied to raise the ship to the next level. Currently, some large canals use pipes running the length of the level to give an equal discharge and to fill up the lock faster.
Earlier these locks used to be manually operated but of late hydraulic power is used to operate these locks.
The canal locks or watertight chambers vary in length from the smallest at 120 ft to the largest at 1,200 ft. They used to be made of timber or stone earlier but are gradually being replaced by concrete and steel.
Among the well-known canals are the 40-mile long Panama Canal and the Suez Canal. The Panama Canal connects the Pacific and Atlantic Oceans and separates North and South America. The Suez Canal in Egypt connects the Red Sea and the Mediterranean Sea.