Water covers almost 75% of Earth's surface, and land makes up the other 25%, totaling about 57.5 million square miles. The land area of the world is divided into seven large land masses, called continents: North America, South America, Europe, Asia, Africa, Australia, and Antarctica. Geography has played a large part in shaping their histories and cultures.
The third largest continent, North America's coasts touch the Pacific, Atlantic, and Arctic Oceans as well as the Caribbean Sea around the West Indies. Twenty-three countries make up North America; two, Canada and the United States, account for more than ¾ of the total land area. Its climate varies extremely, from bitter cold in northern Canada to unbearable heat on the Mexican coast. The physical features differ as you move across the continent, from mountains to flat plains. As a result of these climate and geography differences, North America contains all biome types. Major landmarks of North America include Lake Superior on the Canada-U.S. border, the largest freshwater lake in the world; Death Valley in California, the hottest region on the continent; and Mount McKinley in Alaska, North America's highest mountain.
South America has 12 countries across 6.89 million square miles, the biggest of which is Brazil. On the northwest coast, Panama links the continent to Central America, a sub-region of North America. Among the most noteworthy features of South America are the Andes Mountains that run along the western border. An unbroken series of high plateaus and higher peaks make up the Andes, the world's longest mountain range at more than 5,000 miles. The equator cuts through the northern part of South America, and the Tropic of Capricorn cuts through the middle. Because of its range of elevations, South America divides into many different biomes, but its most well-known is the Amazon rain forest, the largest tropical rain forest in the world, which covers 2.6 million square miles and is home to more than 1,400 types of mammals.
Though it's the second-smallest continent in the world, Europe has 44 countries, almost as many as Asia, the largest continent. Some geographers describe Europe as a peninsula of peninsulas, as water surrounds the continent on three sides and many of the regions of Europe are peninsulas, too, such as the Scandinavian and Italian peninsulas. You can divide Europe into the four regions of Western Uplands, North European Plain, Central Uplands, and Alpine Mountains. The climate can range from arctic to Mediterranean. Europe has many mountains, including the Alps that pass through eight countries and extend for 750 miles.
The largest and most populated continent in the world, Asia has a variety of geographic features, including mountains, plains, and deserts. The continent is made of 48 countries and stretches as far north as Russia, as far east as Japan, as far south as Indonesia, and as far west as Saudi Arabia. Asia has both the highest point on Earth, Mount Everest in the Himalayas, and the lowest point, the Dead Sea in Israel. Many parts of Asia aren't suitable for people to live in, including large desert regions such as the Gobi Desert of China and Mongolia, places with poor weather conditions such as the Kazakh Steppe of Kazakhstan, and mountainous places such as China's Qinling Mountains.
Separated from Asia by the Isthmus of Suez and the Suez Canal, Africa is the second-largest and second-most-populated continent. When Europeans colonized parts of Africa in the 19th century, largely because they wanted the continent's precious metals, it shaped much of what Africa is like today. Deserts and dry land cover 60% of Africa, making it the hottest and second-driest continent. The Sahara Desert, the largest hot desert in the world, dominates northern Africa, and because it's so hot and dry, it's home to only a few million people, mostly nomads. South of the Sahara, several other ecosystems cover Africa, including savanna around the equator. Unlike the other continents, Africa has very few mountains; much of the land is flat.
For a long time, the Australian continent was unknown because of its faraway location "down under." It is the smallest continent, and the biggest part of it is the country of Australia. The islands of New Guinea to the north and Tasmania to the south are also part of the continent of Australia. Most of the population lives in the southwest and southeast of the country of Australia, where the climate is milder. The less populated areas are called the Australian Outback, which contains deserts as well as tropical rain forests. The world's largest coral reef system, the Great Barrier Reef, finds its home on the northeast coast of Australia.
Antarctica is the coldest, driest continent. Not until the early 20th century did explorers try to travel over its difficult geography. The combination of glacier ice that keeps plants from growing, high winds, steep slopes, and high altitude make Antarctica a hard place for humans to live: Nobody lives there permanently, but scientists live there for long stretches of time while they study the climate and wildlife. Antarctica has been called the highest continent, not because it has many mountains but because of the thickness of the glacier ice, which has built up to more than 2.5 miles thick in some areas. Along the coast, pieces of ice break off and float out to sea as icebergs.