THE OCEANS AND THE SEAS - 2 - ANSWERS

1. A. Strait of Hormuz

The Strait of Hormuz is a strait between the Persian Gulf and the Gulf of Oman. It provides the only sea passage from the Persian Gulf to the open ocean and is one of the world's most strategically important choke points. On the north coast lies Iran and on the south coast the United Arab Emirates and "Musandam", an exclave of Oman. The strait is about 167 km long, with a width varying from about 96 km to 39 km.

A third of the world's liquefied natural gas and almost 25% of total global oil consumption passes through the strait, making it a highly important strategic location for international trade.

1. C. White Sea

(Location of White Sea, Red Sea, Black Sea and Yellow Sea - coloured as per their name)

The White Sea is one of four seas named in English after common color terms — the others being the Black Sea, the Red Sea and the Yellow Sea. All the above four seas are located in the Northern Hemisphere and the White Sea is located at the highest latitude (i.e. farthest from the Equator) as an almost landlocked extension of the Arctic Ocean indenting the shores of northwestern Russia connected to the more northerly Barents Sea by a long, narrow strait at 65 Degree North latitude in comparison to the Black Sea (44 Degree North), the Red Sea (22 Degree North) and the Yellow Sea (35 Degree North).

3. C. Sunda Strait

"Krakatoa" (Krakatau) is a small volcanic island located in the Sunda Strait which connects the Java Sea to the Indian Ocean, between the islands of Java and Sumatra. At the time of its famous eruption in 1883, the region was part of the Dutch East Indies; it’s now part of Indonesia.

A previous major eruption, likely in the fifth or sixth century A.D., is thought to have created Krakatoa and two nearby islands, "Lang" and "Verlatan", as well as the undersea caldera (volcanic crater) between them. By 1883, Krakatoa was made up of three peaks: "Perboewatan", the northernmost and most active; "Danan" in the middle; and the largest, "Rakata", which formed the southern end of the island.

Krakatoa was last thought to have erupted some two centuries earlier, in 1680, and most people believed it was extinct. But in May 1883, people reported feeling tremors and hearing explosions, first in western Java and then on the other side of the Sunda Strait in Sumatra.

(An 1888 lithograph of the 1883 eruption of Krakatoa)

Around 1 p.m. on August 26, 1883 a volcanic blast sent a cloud of gas and debris some 15 miles into the air. It would be the first in a series of increasingly powerful explosions over the next 21 hours, culminating in a gigantic blast around 10 am on August 27 that propelled ash some 50 miles into the air and could be heard as far away as Perth, Australia (a distance of some 4500 kms). About 9 square miles of the island, including both "Perboewatan" and "Danan" peaks of the island, plunged underwater into the caldera ("a large cauldron-like hollow that forms shortly after the emptying of a magma chamber/reservoir in a volcanic eruption") to a depth of some 820 feet below sea level. Krakatoa’s violent eruption killed more than 36,000 people.

(The approximate extent to which the Krakatoa eruption blasts were heard)

In 1927, a fourth island, Anak Krakatau, or "Child of Krakatoa", emerged from the caldera formed in 1883. There has been new eruptive activity in the island since the late 20th century, with a large collapse causing a deadly tsunami in December 2018. Like all volcanic eruptions, Krakatoa’s can be traced to the movement of the tectonic plates that make up the Earth’s crust. Krakatoa is directly above the subduction zone of the Eurasian Plate and the Indo-Australian Plate where the plate boundaries make a sharp change of direction, possibly resulting in an unusually weak crust in the region.

(The Subduction Zone of the Eurasian Plate and the Indo-Australian Plate near Krakatoa, Indonesia)

Indonesia today has over 130 active volcanoes, the most of any nation.

4. C. Sargasso Sea

The Sargasso Sea is a region of the Atlantic Ocean bounded by four currents forming an ocean gyre. Unlike all other regions called seas, it has no land boundaries.

It is distinguished from other parts of the Atlantic Ocean by its characteristic brown Sargassum seaweed and often calm blue water. While there are many different types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbors species of sargassum that are 'holopelagi' - this means that the algae not only freely floats around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean. Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for shrimp, crab, fish and other marine species that have adapted specifically to this floating algae.

The sea is bounded on the west by the Gulf Stream, on the north by the North Atlantic Current, on the east by the Canary Current, and on the south by the North Atlantic Equatorial Current, a clockwise-circulating system of ocean currents termed the "North Atlantic Gyre". It lies between 70° and 40° W longitude and 20° to 35° N latitude and is approximately 1,100 km wide and 3,200 km long. Bermuda is near the western fringes of the sea.

5. B. North Sea

North Sea, the northeastern arm of the Atlantic Ocean, is located between the British Isles (England and Scotland) and the mainland of northwestern Europe and covering an area of 220,000 square miles. An inland sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and to the Arctic Ocean through the Norwegian Sea in the north.

("Dogger Bank", one of the major fishing zones in the world is located in a shallow area of the North Sea at about 100 kilometres off the east coast of England)

The North Sea has long been the site of important European shipping lanes as well as a major fishery. The coast is a popular destination for recreation and tourism in bordering countries, and more recently the sea has developed into a rich source of energy resources, including fossil fuels, wind, and early efforts in wave power.

(A map from Ptolemy's Geography showing the "Oceanus Germanicus" - "German Ocean")

Historically, the North Sea has featured prominently in geopolitical and military affairs, particularly in Northern Europe. It was also important globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. As Germany's only outlet to the ocean, the North Sea continued to be strategically important through both World Wars.

(Edmond Halley's solar eclipse 1715 map showing "The German Sea")

Until the late 19th century, the North Sea has been mentioned as the "German Ocean" or "German Sea" in many important maps (including the map from Ptolemy's "Geography" and Edmond Halley's solar eclipse 1715 map).