6 Narrow Waterways That Have Been Exploited for Trade and Power

With one side in Europe and the other in Asia, the Bosporus and the Hellespont/Dardanelles link the Mediterranean and Black seas. Since ancient times, invading armies have crossed them in both directions, from Persians advancing on Greece in the fifth century B.C., and Alexander the Great crossing the other direction to invade Persia in 334 B.C. The Roman emperor Constantine established Constantinople on the Bosporus in A.D. 330, and the city’s dominance of trade powered the Byzantine Empire until it finally fell to the Ottomans in 1453.

For centuries, control of the Bosporus and Dardanelles turned the Black Sea into the single-ruler “Ottoman Lake.” The straits were finally opened to Russian merchant ships in 1774, and the presence of Russia’s growing naval power on the Black Sea became a driving factor in the Crimean War of the 1850s. During World War I, Ottoman closure of the straits helped strangle the Russian Empire and spurred the costly British-led effort to capture the Dardanelles at Gallipoli. The 1936 Montreux Convention gave Turkey the right to control military passage through the straits, a power it invoked most recently following Russia’s 2022 invasion of Ukraine.

From the Pharaonic era to the Cold War, the chokepoints at the northern and southern ends of the Red Sea have been crucial crossroads between Africa, Asia, the Mediterranean Sea and the Indian Ocean. Around 600 B.C., Pharaoh Necho II began digging the Nile-Red Sea Canal, which operated in various forms for more than 1,000 years. During the Islamic era, Egypt’s rulers controlled the growing spice trade from Asia, spurring Portuguese navigators to pioneer a new sea route around the southern tip of Africa.

In 1869, the modern Suez Canal opened under the control of a French-led company. In 1875 Great Britain bought out Egypt’s shares in the canal before occupying Egypt outright in 1882. Although Britain already controlled the route around the Cape of Good Hope to India, Suez became an important link for its imperial ambitions in Asia.

Both World Wars saw failed attempts to seize the Suez Canal from the British. In 1956, Egyptian President Gamal Abdel Nasser nationalized the canal, prompting the Suez Crisis, during which pressure from the United States and the United Nations forced Britain, France and Israel to abandon their attempt to retake the canal.

Following the 1967 Six-Day War, the Suez Canal was closed for nearly eight years. Today the Red Sea shipping route remains fragile, fraught with concerns about Somali piracy and Houthi strikes near the southern Bab el-Mandeb passage, as well as the limitations of the narrow canal, which was blocked for six days in 2021 when the container ship Ever Given became lodged sideways after running aground during high winds and reduced visibility.

There are three natural waterways that link the Baltic Sea with the North Sea and the broader Atlantic, and Denmark once controlled them all. The most important is the Øresund, a narrow strait between present-day Denmark and Sweden, guarded by Kronborg Castle in Elsinore, the setting of Shakespeare’s "Hamlet." Strategic geography and a once-thriving herring fishery fueled conflicts between the Danes and the Hanseatic League, a powerful alliance of northern European merchant cities heavily involved in the Baltic fish trade.

Denmark controlled both sides of the Øresund until 1658 and was able to levy the Sound Dues on passing ships, which at times supplied as much as two-thirds of the Danish Crown’s revenues. Multiple conflicts with Sweden over the Øresund’s eastern shore eventually broke Denmark’s chokehold on the strait. Denmark collected the Sound Dues until the 1857 Convention of Copenhagen, when European powers offered a one-time lump-sum payment in exchange for ending the tolls and opening the Danish straits to toll-free international navigation.

Running 500 miles between the Malay Peninsula and the island of Sumatra, the Strait of Malacca is the most important maritime passage between the Indian and Pacific oceans, linking Africa, Arabia, Persia and India with China. From the A.D. 600s through the A.D. 1000s, the Strait of Malacca was controlled by Srivijaya, a Sumatran empire that dominated trade and spread Buddhism throughout the region. By the late 1200s, the Strait was controlled by Singhasari, a Javanese Hindu-Buddhist kingdom.

The port of Malacca flourished under protection from China’s Ming Dynasty. Ruled by Muslim sultans, Malacca became a multicultural port and an important hub for the spread of Islam in Southeast Asia. In the early 1500s, the Portuguese arrived in the strait, capturing Malacca in 1511. Shortly thereafter the Portuguese colonial official Tomé Pires wrote that “Whoever is lord of Malacca has his hand on the throat of Venice.”

In the 18th and 19th centuries, the British built up ports along the strait including Penang and Singapore, the latter of which became a free trade hub. These outposts facilitated the British Empire’s tea and opium trade with China, and the later export of Malayan rubber and tin. During World War II, Japan captured Singapore to ensure its access to oil from the Dutch East Indies (now Indonesia). In the postwar era, the Strait of Malacca has remained a vital trade route, with roughly one-quarter of world trade running through it.

Flanked by the mountainous Pillars of Hercules, the Mediterranean Sea’s outlet to the Atlantic represented the edge of the known world beyond which, the fifth century B.C. Greek poet Pindar wrote, lay only “western darkness.” As early as 1100 B.C. the Phoenicians founded the port of Gadir (present-day Cádiz) just beyond them to control Atlantic coastal tin and silver routes.

Like the Hellespont, the Strait of Gibraltar was important as a maritime trade outlet and a link between continents. In 711, Tariq ibn Ziyad crossed the strait with 7,000 men, beginning the Islamic conquest of Spain and giving Gibraltar its name (from Jabal Tariq, or “Mountain of Tariq”). In 1462, the Kingdom of Castile retook Gibraltar, 30 years before the fall of Granada and the end of Islamic al-Andalus.

Over the next several centuries the Strait of Gibraltar remained a contested borderland. From their bases on the African side of the strait, Barbary pirates harried trade and launched raids further afield. An Anglo-Dutch force seized the Rock of Gibraltar in 1704. In 1713, the Treaty of Utrecht ceded it to Britain, where it has remained despite Spanish efforts to reclaim the British enclave.

In the mid-1500s, many European maps of the Americas began to depict the Strait of Anián, a hypothetical northern sea route to Asia. Explorers from John Cabot in the 1490s to Henry Hudson in the early 1600s probed the Atlantic coast of North America while on the Pacific coast, Juan Rodríguez Cabrillo and Francis Drake sailed along the coast of California looking for possible outlets. The fruitless quest for the Northwest Passage shaped European colonization of North America along the continent’s rivers and bays.

Through the 19th century, European explorers and the powers that backed them pushed into the Arctic in search of the route. In fact, Native peoples had made the journey millennia earlier. Both the Paleo-Inuit and Thule cultures had moved across the northern Arctic coastal waterways over multiple generations centuries before Europeans arrived, and explorers nearly always relied on Indigenous groups’ deep knowledge of regional geography and survival skills. In 1906, Norwegian polar explorer Roald Amundsen completed the first known navigation of the Northwest Passage in a single ship, in a journey that took him three years.

In 1969, the icebreaking oil tanker Manhattan became the first commercial vessel to complete the Northwest Passage, triggering an international controversy as Canada asserted that the route passed through its internal waters without permission. As global warming brings longer periods of ice-free navigation to more of the Arctic, questions of security, sovereignty and control have given the once quasi-mythical Northwest Passage renewed relevance.