The canal, opened in 1869 after almost a decade of work, has been a main revenue earner for Egypt and a 20th century symbol of independence.
The pan-Arabist president Gamal Abdel Nasser nationalised the canal in 1956, which was until then run by the British- and French-owned Suez Canal Company, sparking the Suez crisis in which Britain, France and Israel invaded parts of Egypt.
The waterway has continued to play a key role in global commerce and is an important route for oil traffic.
In 2013, 4.6 percent of global oil and petroleum products passed through the Suez Canal or the SUMED pipeline that provides an alternative route from the Red Sea to the Mediterranean, according to the US Energy Information Agency.
In 2007, traffic through the canal amounted to 7.5 percent of global maritime trade, according to the World Shipping Council.
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The 72-kilometre (45-mile) long expansion is projected to cut the waiting period for ships from 18 hours to 11 hours and allow two-way passage.
It was built in less than a year for about $9 billion (7.9 Euros), mostly financed by investment certificates sold to Egyptians.
The project consists of 37 kilometres of new, parallel waterway and 35 kilometres of deepening and widening of the existing canal.
A maximum 49 ships a day can pass through the canal at present. The Suez Canal Authority says the expansion could almost double the number by 2023.
The government hopes the project will more than double revenues from Suez Canal tolls, a key income generator for Egypt, from the $5.3 billion projected for 2015 to $13.2 billion in 2023.
Experts say it is not yet clear, however, what impact the improvements to the 192 kilometre waterway will have on world trade.