A ship canal is a canal especially constructed to carry ocean-going ships, as opposed to barges. Ship canals can be enlarged barge canals, canalised or channelized rivers, or canals especially constructed from the start to accommodate ships.

For a canal to qualify as a ship canal, it must have a minimum depth of at least 5 metres (16.4 feet), although many are much deeper. The purpose of a ship canal is:

1. To create a shortcut and avoid lengthy detours.
2. To create a navigable shipping link between two land-locked seas or lakes.
3. To provide inland cities with a direct shipping link to the sea.

List of important ship canals:

1. White Sea-Baltic Canal in Russia, 141 miles (227 km) long, opened in 1933, is partly a canalised river, partly an artificial canal, and partly some natural lakes.
2. Suez Canal in Egypt, 100 miles (160 km) long, opened in 1869, links the Mediterranean Sea to the Red Sea.
3. Volga-Don Canal in Russia, 62 miles (100 km) long, opened in 1952, connects the Black, Azov, and Caspian Seas.
4. Kiel Canal in Germany, 60 miles (98 km) long, opened in 1895. Shortens the passage between the North Sea and the Baltic Sea.
5. Houston Ship Canal in the USA, 56 miles (91 km) long, connects Houston, Texas to the Gulf of Mexico.
6. Alphonse XIII Canal in Spain, 53 miles (85 km) long, opened in1926, mostly canalised river. Links Seville to the Gulf of Cadiz .
7. Panama Canal in Panama, 51 miles (82 km) long, opened in 1914. Links the Caribbean Sea to the Pacific Ocean, creating a shortcut.
8. Manchester Ship Canal in England, 35 miles (57 km) long, opened in 1894. Links Manchester to Irish Sea.
9. Welland Canal in Canada, 28 miles (45 km) long, opened in 1931. Links Lake Erie to Lake Ontario.

Navigability

The standard used in the European Union for classifying the navigability of inland waterways is the European Agreement on Main Inland Waterways of International Importance (AGN) of 1996, adopted by The Inland Transport Committee of the United Nations Economic Commission for Europe (ECE), which defines the following classes. (This table is incomplete.)