Canal

A canal is a man-made waterway or channel that is built for navigation, irrigation, drainage, or water supply. When the word is used today however, it is usually in the context of transport or navigation by boats. Canal transport should not be confused with navigating on a river, because a canal is entirely artificial (although canals are in many cases connected with a natural body of water).

There are two major types of transport canals. One is an inland waterway, or water route, that either follows the lay of the land or has locks. The other is a canal that is built to shorten a sea route. Examples of the latter are the Suez Canal, which connects the Mediterranean and the Red Sea, and the Panama Canal, which shortens the voyage from Europe to America's west coast by 3,000 m (4,800 km). From the earliest times, canals were built because they were the simplest and cheapest way of moving heavy goods.

Canals can be among the most complicated engineering projects of their times. A canal across the Isthmus of Panama, for example, was first envisioned by Spanish explorers in 1513. The French began construction of a canal across the isthmus in 1880, but abandoned work in 1889. Excavation of the canal was resumed by the United States in 1904 and the Panama Canal finally opened in 1914. As many as 40,000 workers were employed at various times during the construction of the Panama Canal, which required the construction of towns to house workers, railroads to move supplies and enormous amounts of excavated soil and rock, and the invention of new kinds of construction equipment. Perhaps the most prominent engineering accomplishment during construction of the Panama Canal was the Culebra Cut, a 8.75-mi (14-km) excavation across the continental divide that was plagued by landslides. The total amount of soil and rock excavated along the Culebra Cut was estimated to have been about 100,000,000 cubic yards (76,500,000 cubic meters), or the equivalent of more than 8 million large dump truck loads. Monitoring of landslides along the Culebra Cut persists to this day.

Many long-abandoned inland canals in the United States, British Isles, and Europe are currently the focus of restoration projects. This work, often undertaken by volunteer groups, is being done to repair the effects of decades of neglect, educate the public about the historical significance of canals, and provide new recreational opportunities.