The Isthmus of Suez so obviously provided a short sea route from the Mediterranean to the Indian Ocean and beyond as against the sea voyage around Africa that a canal was dug in antiquity; it fell into disuse, was frequently restored, and finally was blocked about the 8th century. Later there were many projects and surveys, but nothing happened until 1854, when Ferdinand de Lesseps, who had served as a diplomat for France in Egypt, persuaded Saʿīd Pasha, the viceroy of Egypt, to grant a preliminary concession for construction of a new canal across the isthmus. A later report recommended a sea-level lockless canal between Suez and the Gulf of Pelusium, and the original concession was superseded by one granted in 1856 to the Suez Canal Company, an international consortium. The concession was to last for 99 years from the canal’s opening to navigation, after which it was to revert to the Egyptian government; the canal was to be an international waterway, open at all times to all ships without discrimination. In addition to the ship canal, the company undertook to excavate a freshwater canal from the Nile at Bûlâq to Ismailia, with a branch extending to the Suez, to be available for smaller ships. Work on the ship canal lasted 10 years, during which time political, financial, contractual, and physical difficulties were overcome, and the canal was opened on November 17, 1869.

As ultimately constructed, the Suez Canal was a 193-km (120-mile) lockless waterway connecting the Mediterranean and the Red Sea. From its northern terminal at Port Said, the canal passes through the salt marsh area of Lake Manzala, with the freshwater canal running parallel. About 48 km (30 miles) from Port Said, an 11-km (7-mile) bypass built between 1949 and 1951 enables convoys to pass. At about the halfway point the canal enters Lake Timsah and passes Ismailia. Thence the waterway proceeds through the Bitter Lakes and on to Port Tawfīq, the southern terminal on the Red Sea, not far from the town of Suez. Since its construction, the canal has been constantly improved; originally 60 metres (197 feet) wide with a maximum depth of 8 metres (26 feet), it was widened in 1956 to 152 metres (499 feet) at water level and 60 metres (197 feet) at a depth of 11 metres (36 feet), with the main channel 14 metres (46 feet) deep, enabling ships of a maximum draft of 11 metres (36 feet) to navigate the canal. Similar expansions were carried out nearly every decade, and in the first quarter of the 21st century the canal could accommodate ships with a draft of 20 metres (66 feet). In 2015 the Egyptian government finished a nearly $8.5 billion project to upgrade the canal and significantly increase its capacity; nearly 29 km (18 miles) were added to its original length of 164 km (102 miles).

The canal remained open despite much political controversy. Nationalized by Egypt in 1956, it was blocked in 1967 after the Arab-Israeli war and remained so until 1975.

The Panama Canal

After his success with the Suez Canal, Ferdinand de Lesseps was attracted to the Isthmus of Panama, where many projects had been suggested for cutting a canal to join the Atlantic and Pacific oceans and thus make unnecessary the passage around South America. De Lesseps proposed a sea-level route via Lake Nicaragua, but construction difficulties forced him to abandon this project in favour of a high-level lock canal via Panama. Further problems, especially yellow fever among the workforce, halted construction after about 60 million cubic metres (78 million cubic yards) of material had been excavated.

Meanwhile, U.S. interest had been actively maintained, but the situation was complicated by political difficulties and questions of sovereignty. A treaty between Britain and the United States recognized the exclusive U.S. right to construct, regulate, and manage a canal across the isthmus, but Panama was Colombian territory, and the Colombia Senate refused ratification of a treaty with the United States. After a revolt, a treaty was signed with independent Panama that granted the United States exclusive use, occupation, and control of the Canal Zone in perpetuity.

Although preliminary work started in 1904, little real progress was made, because of disputes over the type of canal that should be built. Not until 1906 was the high-level lock plan finally adopted, as opposed to the previously favoured sea-level plan. Largely responsible for this decision was John F. Stevens, who became chief engineer and architect of the canal. Completed in 1914, the canal is 82 km (51 miles) long. At its start from the large harbour area in Limón Bay on the Caribbean Sea, it rises more than 24 metres (80 feet) above sea level to Gatún Lake through the Gatún Locks and is retained at the north by these locks and dam and at the south by the Pedro Miguel Locks and Dam. The waterway then runs through the Gaillard Cut, which channels it through the Continental Divide, then between the Pedro Miguel Locks and Miraflores Lake at an elevation of 16 metres (54 feet), ships to the Pacific Ocean being lowered by them to the Balboa Harbor entrance. Gatún Lake, with its area of 430 square km (166 square miles), is an integral part of the waterway and the principal source of its water. The minimum channel depth throughout the length of the canal is 12 metres (40 feet) and its minimum bottom width is 150 metres (500 feet). There are 23 angles or changes of direction between the entrances. Ships normally travel through the canal under their own power except in the locks, through which they are towed by electric locomotives.

In 1979 control of the canal passed to the Panama Canal Commission, a joint agency of the United States and the Republic of Panama, and complete control passed to Panama on December 31, 1999. Administration of the canal is the responsibility of the Panama Canal Authority (Spanish: Autoridad del Canal de Panamá [ACP]), which answers solely to the government of Panama.