Narrow Waters: Straits and Fjords

The Atlantic Ocean meets the Mediterranean Sea here, and the gap shrinks to about 14.2 kilometers between the Spanish and Moroccan coasts. It is the nearest point where Europe and Africa face each other, and ferries cross in as little as 35 minutes.

Turkey's strait links the Black Sea to the Sea of Marmara and forms part of the boundary between Asia and Europe, with Istanbul straddling both shores. It narrows to as little as 700 meters, which makes it the narrowest strait used for international navigation.

The only sea passage from the Persian Gulf to the open ocean runs about 167 kilometers and narrows to 39 kilometers wide, between Iran and the Musandam Peninsula of Oman. The entry describes it as a chokepoint for a quarter of the world's seaborne oil trade.

Between the Malay Peninsula and the Indonesian island of Sumatra, this strait connects the Pacific side to the Indian Ocean. It averages only about 25 meters deep, a shallowness that gave its name to the Malaccamax ship size standard.

About 82 kilometers across at its narrowest, it separates Russia's Chukchi Peninsula from Alaska and joins the Pacific to the Arctic Ocean. In colder ages, when sea level fell, the seabed here became the Beringia land bridge linked to early human migration.

Norway's longest and deepest fjord reaches 205 kilometers inland and 1,308 meters down, yet is never wider than 4.5 kilometers. Nicknamed the King of the Fjords, it shows the same narrow shape as the straits.

The fifth-longest fjord in the world extends about 179 kilometers inland and varies from 2 to 10 kilometers wide. The entry says it began as the ice sheet filling the valley started melting around 8000 BCE, so its narrow arm is a glacier's work.

Only about 15 kilometers long and 1.5 kilometers wide at most, this branch off the Sunnylvsfjorden is a small fjord with steep, waterfall-lined walls. In 2005 UNESCO inscribed it jointly with the Naeroyfjord as the West Norwegian Fjords.