International canals are man-made constructions, waterways which link two geographically separate marine areas and pass through the territory of one or more States, which are regarded as the waterway's "owners". The canal is therefore considered as forming part of internal waters subjected to the territorial sovereignty of the neighbouring State(s). However, the canal is also an international maritime passageway connecting two free seas. Its legal regime has thus often been internationalized under conventional law, in order to guarantee freedom of passage to foreign vessels. Examples include the Convention of Constantinople of 1888 for the Suez Canal, the Panama Canal Treaty of 1977 and the Treaty of Versailles in 1919 for the Kiel Canal.
A strategic passageway, the canal allows for a simple transit operation to shorten the routes taken by international maritime navigation.
While observing the principle of unrestricted use and freedom of navigation consecrated by international law, the bordering State or States nevertheless continue(s) to exercise its/their full sovereignty by issuing regulations, collecting taxes and taking all self-defensive measures.
Thus, in spite of its status as an international passageway, the Suez Canal  forms an integral part of Egypt's territory.
The Convention of Constantinople signed on October 29th, 1888, decrees a very emphatic status of neutrality for this waterway, stating in the following terms that this canal "shall always be free and open to vessels of commerce or of war, without distinction of flag… in time of war as in time of peace… The Canal shall never be subjected to the exercise of the right of blockade" .
 The Suez Canal is a feat of civil engineering 193.3 km long, 280 to 345 m wide and 22.5 m deep, which links the city of Port Said on the Mediterranean Sea to the town of Suez on the Gulf of Suez (Red Sea) via three natural lakes. Commenced in 1859 by Ferdinand de Lesseps, the cutting of the canal was only completed in 1869. It enables ships to sail from Europe to Asia without having to go all around Africa. Before it was opened in 1869, merchandise had to be transported overland between the Mediterranean and the Red Sea.
 Convention of Constantinople, article 1.