The Suez Canal, the 193-km (120-mile) artificial sea-level waterway cutting through the Isthmus of Suez in Egypt, is the sole maritime passage connecting the Red Sea to the Mediterranean Sea. Its control is unambiguous.
The canal is owned, operated, and maintained by the Suez Canal Authority (SCA), a state-owned entity of the Arab Republic of Egypt. Established in 1956 after President Gamal Abdel Nasser nationalized the Universal Suez Ship Canal Company (formerly French-British owned), the SCA sets tolls, manages traffic, and oversees expansion projects.
The Convention of Constantinople (1888) guarantees the canal's openness to "every vessel of commerce or of war, without distinction of flag" in both peace and war. Egypt honors this treaty, though it has temporarily restricted passage during conflicts (1956, 1967–1975).
In short: Egypt controls the passage. No other nation shares operational authority.