The Sinai Peninsula, or simply Sinai (now usually SY-ny) (Arabic: سِينَاء, Egyptian Arabic: سينا, Coptic: Ⲥⲓⲛⲁ), is a peninsula in Egypt, and the only part of the country located in Asia. It is between the Mediterranean Sea to the north and the Red Sea to the south, and is a land bridge between Asia and Africa. Sinai has a land area of about 60,000 km² (23,000 sq mi) (6 percent of Egypt's total area) and a population of approximately 600,000 people. Administratively, the vast majority of the area of the Sinai Peninsula is divided into two governorates: the South Sinai Governorate and the North Sinai Governorate. Three other governorates span the Suez Canal, crossing into African Egypt: Suez Governorate on the southern end of the Suez Canal, Ismailia Governorate in the center, and Port Said Governorate in the north.

In the classical era the region was known as Arabia Petraea. The peninsula acquired the name Sinai in modern times due to the assumption that a mountain near Saint Catherine's Monastery is the Biblical Mount Sinai. Mount Sinai is one of the most religiously significant places in the Abrahamic faiths.

The Sinai Peninsula has been a part of Egypt from the First Dynasty of ancient Egypt (c.  3100 BC). This comes in stark contrast to the region north of it, the Levant (present-day territories of Syria, Lebanon, Jordan, Israel and Palestine), which, due largely to its strategic geopolitical location and cultural convergences, has historically been the center of conflict between Egypt and various states of Mesopotamia and Asia Minor. In periods of foreign occupation, the Sinai was, like the rest of Egypt, also occupied and controlled by foreign empires, in more recent history the Ottoman Empire (1517–1867) and the United Kingdom (1882–1956). Israel invaded and occupied Sinai during the Suez Crisis (known in Egypt as the Tripartite Aggression due to the simultaneous coordinated attack by the UK, France and Israel) of 1956, and during the Six-Day War of 1967. On 6 October 1973, Egypt launched the Yom Kippur War to retake the peninsula, which was unsuccessful. In 1982, as a result of the Egypt–Israel peace treaty of 1979, Israel withdrew from all of the Sinai Peninsula except the contentious territory of Taba, which was returned after a ruling by a commission of arbitration in 1989.

Today, Sinai has become a tourist destination due to its natural setting, rich coral reefs, and biblical history.