Some bodies of salt water that are called seas are really lakes. These bodies of water were part of prehistoric oceans or seas. Tectonic shifts blocked their access to larger bodies of water, and they are now completely surrounded by land.
Why is the Black Sea not a lake? Because it's a part of the global ocean. Its waters are saline, it sits at global sea level, and its connection to the Mediterranean Sea via the Bosporus and Dardanelles at Istanbul is one of the busiest shipping straits on Earth.
Geology of Lake InferiorLake Inferior is an underground lake that is located beneath Lake Superior. It is believed to be formed by a process known as karstification, which is the dissolution of limestone and dolomite rock. This process creates sinkholes, caves, and underground rivers and lakes.
1. Lake Superior is actually not a lake at all, but an inland sea. 2. All of the four other Great Lakes, plus three more the size of Lake Erie, would fit inside of Lake Superior.
Lake Superior contains fresh water, is uphill from the ocean by far more than the tides can reach (its mean elevation is 600 feet or so), and is downhill from a number of fresh-water inputs in a well watered part of the US and Canada.
The Ojibwe name for the lake is gichi-gami (in syllabics: ????, pronounced gitchi-gami or kitchi-gami in different dialects), meaning great sea. Henry Wadsworth Longfellow wrote this name as Gitche Gumee in the poem The Song of Hiawatha, as did Gordon Lightfoot in his song The Wreck of the Edmund Fitzgerald.
Spanning nearly 32,000 square miles, Lake Superior is not only the largest freshwater lake in the world (by surface area) but it is also one of the largest lakes in the world, second only to the Caspian Sea.
Lake Superior has been described as the most oligotrophic lake in the world because it's so nutrient poor. It still has plenty of nutrients to support the plants and animals that live in it though. This lack of nutrients keeps the water as clear as you see it here.
The best place to swim or float in the lake is at Antelope Island State Park, where white oolitic sand beaches provide easy access to the lake without the brine flies that are prevalent on other areas of the shoreline. The beach area also has showers to rinse off the salty water.
The most saline water body in the world is the Gaet'ale Pond, located in the Danakil Depression in Afar, Ethiopia. The water of Gaet'ale Pond has a salinity of 43%, making it the saltiest water body on Earth (i.e. 12 times as salty as ocean water).