The highest and deepest places

The floor of the Challenger Deep lies 10,924 metres below the sea surface, 2,075 metres farther down than Everest rises up.

Measured from sea level

Heights on maps are measured from mean sea level, the average height of the sea surface. By that measure the highest point on Earth is Mount Everest on the border of China and Nepal, at 8,849 metres. All ten of the world’s highest mountains are in Asia, in the Himalaya and Karakoram ranges, and every one is above 8,000 metres. The second highest, K2 on the border of China and Pakistan, reaches 8,611 metres.

Every continent has its own highest point, and the list is a good way to tie mountains to the map. South America has Aconcagua in Argentina at 6,960 metres, the highest peak outside Asia. North America has Denali in Alaska at 6,190 metres; United States government lists now call it Mount McKinley. Africa has Kilimanjaro in Tanzania at 5,895 metres, Europe has Elbrus in Russia at about 5,640 metres, Antarctica has the Vinson Massif at about 4,890 metres, and Australia has Mount Kosciuszko at only 2,229 metres.

Tallest is not the same as highest

Mauna Kea, on the island of Hawaii, rises only 4,207 metres above the sea. But its base is more than 70 kilometres offshore and about 6,000 metres down on the sea floor. Measured from base to summit, estimates of its total height run from 9,966 to 10,203 metres, which makes it the tallest mountain on Earth even though Everest is the highest. The difference is only in where you start measuring.

Land below sea level

Some dry land lies below sea level. The lowest exposed point on any continent is the shore of the Dead Sea between Israel and Jordan, about 431 metres below sea level. Africa’s lowest point is Lac Assal in Djibouti at 155 metres below, South America’s is Laguna del Carbón in Argentina at 105 metres below, and North America’s is Death Valley in California at 86 metres below. In Europe the lowest point is the surface of the Caspian Sea, about 28 metres below sea level, and in Australia it is Lake Eyre at about 15 metres below.

Antarctica hides the lowest land of all. Under the Denman Glacier, the rock bed lies more than 3,500 metres below sea level, but it is buried under ice, so no one can stand on it. That is why the Dead Sea shore is usually called the lowest point on land: it is the lowest place where you can walk in the open air.

The ocean trenches

The sea floor goes much deeper than any valley on land. The deepest known point is the Challenger Deep in the Mariana Trench, in the western Pacific, at about 10,924 metres below the surface. If Everest were set on its floor, its summit would still be about 2,075 metres under water. The deepest point of the Atlantic is in the Puerto Rico Trench at 8,605 metres, and of the Indian Ocean in the Java Trench at 7,192 metres. Trenches form where one tectonic plate sinks under another, which is why most of them ring the Pacific.