Mapping the megalakes: The 10 largest waters on Earth

What happens when a lake grows so large that it can be seen from space, creates its own waves, and controls the local weather? It becomes an inland ocean. The world's largest lakes are among the most powerful and striking geographical features on Earth, containing the bulk of our liquid surface fresh water. These huge water bodies are essential for the environment and the economy. So, they are so big and deep that they change what we think about water that is not connected to the ocean.Caspian SeaThe Caspian Sea is actually the body of water that is not connected to the ocean. It is called a sea or a lake because it does not flow into the ocean and it sits in a basin. The Caspian Sea covers 371,000 square kilometers and it touches five countries: Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. The water in the Caspian Sea is not completely fresh; it is a little salty, one-third as salty as the ocean. This is because a time ago it was connected to the ocean. Lake SuperiorLake Superior is on the border of the United States and Canada. It is the biggest freshwater lake in the world. It covers 82,100 square kilometers and it is the biggest of the Great Lakes in North America. This lake is so big that it holds more water than all the other Great Lakes put together; it has about 10% of the fresh water in the world. Lake Superior is really cold and its water is very clear; it also has storms in the autumn. The lake is a route for ships that carry industrial cargo.Lake VictoriaLake Victoria is the lake in the tropics and the biggest lake in Africa. It covers about 68,800 kilometers and three countries share it: Uganda, Kenya and Tanzania. The Caspian Sea and Lake Superior and Lake Victoria are all important water systems. They are all different. They are all vital for the environment and the economy.Named after Queen Victoria, this relatively shallow lake is the primary reservoir for the Nile River. It supports one of the most densely populated rural regions in the world, providing millions of people with a vital source of fish, though it faces severe modern environmental threats from pollution and invasive species like the water hyacinth.Lake HuronAnother titan of North America's Great Lakes system, Lake Huron occupies a surface area of about 59,600 square kilometers. Hydrologically connected directly to Lake Michigan via the wide Straits of Mackinac, the two are technically considered a single lake by scientists, though they are treated separately in geography.Lake Huron boasts the longest shoreline of any of the Great Lakes, largely due to its massive network of islands. Among these is Manitoulin Island, which holds the unique distinction of being the largest freshwater island anywhere in the world. Lake MichiganSlightly smaller than its interconnected neighbor Huron, Lake Michigan covers an area of 58,000 square kilometers. It is unique among the North American Great Lakes because it is the only one located entirely within the borders of a single country: the United States.The lake has an effect on the weather and the land around it in several states, including Michigan, Wisconsin, Illinois and Indiana. The lake is famous for its sand dunes and its southern part has big cities like Chicago and Milwaukee.Lake TanganyikaLake Tanganyika is an amazing natural place. It is in the East African Rift Valley. Lake Tanganyika is the lake with freshwater in the world. It is 673 kilometers long from north to south. Covers 32,900 square kilometers. Lake Tanganyika is the oldest lake and the second deepest lake in the world. It is 1,470 meters deep. Because it is so old and has been alone for long, it has a lot of different kinds of life. There are types of colorful fish that live in Lake Tanganyika that you cannot find anywhere else.Lake BaikalLake Baikal is in the mountains of Siberia, Russia. People think it is the freshwater lake. It is not the lake; it is seventh in size with 31,700 square kilometers. Lake Baikal is very deep and holds a lot more water than any other lake. Baikal is the deepest lake in the world (1,642 meters) and the oldest (25 million years). It contains an incredible 20% of the world's unfrozen surface fresh water—more than all five North American Great Lakes combined. Known as the "Galapagos of Russia," it is home to the Baikal seal, the world's only completely freshwater seal species. Great Bear LakeLocated entirely within the boreal forest of the Northwest Territories of Canada, Great Bear Lake covers 31,000 square kilometers. It is the largest lake situated completely within Canadian borders and intersects the Arctic Circle. Because of its extreme northern location, Great Bear Lake is covered in ice for a significant portion of the year. The water is really cold and clear. This is good for certain kinds of fish that live in a pretty much untouched natural place. Lake MalawiLake Malawi is also called Lake Nyasa. It is the southernmost lake in the African Rift system and it covers 29,600 square kilometers. The countries of Malawi, Mozambique and Tanzania share the shores of Lake Malawi. Lake Malawi is similar to Lake Tanganyika because it is very important for the way living things change over time. Lake Malawi has different kinds of fish than any other lake on Earth. There are hundreds of types of cichlids in Lake Malawi. This makes Lake Malawi an important place for people who study how living things change over time and for people who fish in Lake Malawi.Slave LakeThe tenth biggest lake is Great Slave Lake in Canada. It is 27,200 square kilometers big and it is in the Northwest Territories. It is near Great Bear Lake. It is in a very rough and cold place. Great Slave Lake is the largest lake in North America. It is more than 614 meters deep. The lake is frozen for eight months of the year. When it is frozen, people make roads on the ice to connect the towns that are far away from each other.