The Strait of Gibraltar is the 60-m (36-mi) long channel that separates Europe (Spain) from Africa (Morocco) at the western end of the Mediterranean Sea.

The strait is 13 km (8 mi) across at its narrowest point. Its current is two-layered; the upper layer moves east into the Mediterranean, carrying oxygen and nutrients, and the lower, saline layer moves west, or outward. The strait is deepest in the east; the relative shallowness of the western end (320 m/1,050 ft) causes it to retain the warmth of the Mediterranean's water. The strait is named for the Spanish promontory that was once named Jebel Tariq or Mount Tariq in honor of the Berber leader who began the Muslim conquest of Spain in 711.

Dardanelles

The Dardanelles is the 61-km-long (38-mi) strait between the Aegean Sea and the Sea of Marmara. It is the westernmost section of the waterway that divides Europe from Asia and connects the Mediterranean and Black seas. The narrow (1-6 km/3/4-4 mi) strait lies within present-day Turkey, where it is called the Strait of Çanakkale.

Called the Hellespont in ancient times, the strait is associated with the legend of Hero and Leander. The modern name comes from Dardanus, mythical ancestor of nearby Troy.

Despite unpredictable weather and swift surface currents, the Dardanelles has been a strategic water route-and an object of conquest-throughout history. Long controlled (1402-1918) by the Ottoman Empire, it was a primary factor in the Eastern Question of the 19th century and the scene of an intensive Allied campaign in World War I (see Gallipoli campaign).

Bosphorus

The Bosporus, or Bosphorus, is a narrow strait between Europe and Asia connecting the Black Sea to the Sea of Marmara, which in turn is connected by the Dardanelles to the Aegean Sea, part of the Mediterranean Sea. Istanbul, Turkey, spreads out over both sides. Since ancient times the strait, with a maximum width of 3.7 km (2.3 mi) and a length of 30 km (19 mi), has been strategic for trade and military purposes. In 2004 an estimated 50,000 vessels traversed it, with commuter ferries transporting an estimated 2.5 million people daily.

To prevent a major accident in the crowded waterway, which is often shrouded in fog and is regularly used by giant oil tankers, the Turkish government established more-stringent traffic controls in 2004 that slowed traffic in the channel. It also pushed for the construction of an oil pipeline that would bypass the Bosporus.