Lake Superior: The Largest Freshwater Lake in the World

Lake Superior is the largest among the 5 North American Great Lakes, and the largest freshwater lake in the world by surface area. It is brimming with scenic places and national parks surround it, making it an incredibly beautiful area to visit. Lake Superior is managed by an agreement between the United States and Canada, and by the Canadian province of Ontario and the American states of Michigan, Wisconsin and Minnesota.

Lake Superior Stats

Lake NameLake Superior
CountryUnited States
Surface area81843.920
Maximum depth406.0
Average depth146.7
Lake typeGlacial
Catchment area209219.50
InflowsNipigon, St Louis, Pigeon, Pic, White, Michipicoten, Kaministiquia
OutflowsSt Marys
Shore length5248.36
Mixing typeDimictic
SettlementsThunder Bay, Duluth, Sault Ste. Marie (Ontario), Sault Ste. Marie (Michigan), Marquette, Superior
Residence time48410.3
FrozenNovember to April
Average discharge2869.953
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Name Origins

The lake is called "gichi-gami" by the Ojibwe, which means "be a great sea". However, other sources indicate that the name is actually Ojibwe Gichigami, which means "Ojibwe's Great Sea". The first dictionary written for the Ojibway language by Father Frederic Baraga in 1878 indicates that the Ojibwe name is "Otchipwe-kitchi-gami", which means " reflecting Ojibwe Gichigami".

The lake was referred to as "le lac supérieur" by the first French explorers who approached the lake from the Ottawa River and Lake Huron in the 17th century. The literal translation is the "upper lake", meaning the lake above Lake Huron. The lake was also known under the name of Lac Tracy in the 17th century. Jesuit missionaries named it that way after Alexandre de Prouville de Tracy. When the British gained control of the region from the French in the 1760s, they named the lake "Superior" because of its great size.

Geography and Hydrography

The lake is located at the border between the United States and Canada, and is shared by the American states of Minnesota, Wisconsin and Michigan and the Canadian province of Ontario. Lake Superior is also the third largest freshwater lake in the world by volume and the first in North America.

St. Marys river drains Lake Superior into Lake Huron via the Soo Locks. As already mentioned, Lake Superior is the largest freshwater lake in the world by surface area and the third largest by volume, behind Lake Baikal and Lake Tanganyika. Its volume is so great, that it could hold all the water of the rest of the Great American Lakes, plus that of 3 more Lake Erie. The lake holds 10% of all the world’s surface fresh water that is not frozen in an ice cap or glacier.

It’s surface area of 82,103 km2 (or 31,700 square miles), makes it roughly the same size as Austria or South Carolina. It’s length it 560 kilometers (or 350 miles) and has a maximum width of 257 kilometers, or 160 miles.

The average depth of the lake is 147 meters (or 483 ft), while the maximum depth reaches 406 meters (1,332 ft). The total water volume in the lake is 12,100 km³, or 2,900 cubic miles. If the water in Lake Superior covered the landmass of both North and South America, the sheet of water would be 30 centimeters in depth. The lake has a total shore length of 4,387 km or 2,726 miles, including islands.

The lowest point of Lake Superior was reached for the first time on July 30th, 1985 by the American limnologist J. Val Klump. The bottom of the lake, situated 233 meters (or 733 feet) below sea level, is actually the lowest point in the continental United States, and the second-lowest point on the entire North American continent, after the bottom of the Great Slave Lake, which sits 458 meters (1,503 feet) below sea level.

The temperature at the surface of Lake Superior varies seasonally. However, temperature below 200 meters (660 ft) remains constant at about 4 °C (39 °F). The lake is seasonally stratigraphic due to variations in temperature. However, twice every year the water reaches a uniform temperature of 4 °C (39 °F), and waters mix thoroughly. This makes Lake Superior dimictic. The water retention time in the lake is 191 years. Lake Superior is also well-known for its big waves during storms. These waves can reach 6 meters (20 feet), but waves of 9 meters (30 feet) have also been recorded. The lake is amazingly clean, but also cold. Transparency can sometimes exceed 23 meters (75 ft).


More than 200 rivers drain into the lake, among which the most notable include: St. Louis River (309 km or 192 miles), Pic River (150 km or 93 miles), Kaministiquia River (95 km or 59 miles), Michipicoten River (81 km or 50 miles), Bois Brule River (71 km or 44 miles), Pigeon River (50 km or 31 miles), and Nipigon River (48 km or 30 miles).

Drains into Lake Huron

Lake Superior is drained into Lake Huron by the St. Marys River (120 km or 75 miles). Since the river’s upper end features rapids, the Soo Locks were built, which enable ships to navigate freely between Lake Superior and Lake Huron and bypass the rapids. The difference in altitude between the 2 lakes is 8 meters.

The lake evaporates fastest from October to February, contrary to one might guess. This happens because cold and dry air from Canada moves over Lake Superior’s warmer surface, causing evaporation.


Most pollutants, such as dioxin, mercury and PCBs, fall from the atmosphere via dust or precipitation. The concentrations of the toxins are lower than in the other Great Lakes, but they can accumulate in the food web and harm predators.

Record Low Water Level in 2007

Water used to flow naturally out of Lake Superior through the St. Marys River until 1887. However, by 1921 a series of power canals, locks and gates were built on the river, in order to facilitate transport and to generate hydroelectric power. Water levels in the lake are regulated by the International Lake Superior Board of Control, established in 1914.

The record low in the water’s level was reached in September 2007, which was slightly lower than the previous record from 1926. Water level returned to normal in a few days.

Lake Superior’s highest water levels are reached in October and November. Still, the highest recorded level of the lake was recorded in the summer of 1985, at 0.71 meters (or 2.33 feet) above datum (the usual high-water mark is 0.36 meters or 1.17 feet above datum).
The lake reaches its lowest water levels between March and April. During the 1926 record low, water level reached 0.48 meters or 1.58 feet below datum, while a normal low-water mark is 0.10 meters (0.33 feet) below datum. The entire first half of 1926 recorded very low months, a continuation of similar record low levels between October and December 1925.

Possibly Ice-Free by 2040

Studies at the University of Minnesota Duluth suggest that Lake Superior has warmed faster than the area that surrounds it. While the surrounding air temperature has increased by approximately 1.5 °C (or 2.7 °F) since 1979, the temperatures at the lake’s surface have increased by 2.5 °C (4.5 °F). This may be due to the decrease in the lake’s ice cover, which causes more solar radiation to penetrate through the water during winter. Lake Superior freezes completely once every 20 years, but this could change by 2040 if the alarming trend continues, and the lake could be completely ice-free.

The great size of Lake Superior makes the region’s humid continental climate milder (as opposed to Nova Scotia for example). This means that the lake can greatly influence daily weather through the phenomenon known as the "lake effect". This is mainly due to the fact that its surface water is slow to react to temperature changes, which moderates air temperatures in summer and winter months. In autumns, the mountains and hills that surround the lake hold fog and moisture.

The "lake effect" can also greatly enhance the power of the storms through extra moisture and stronger winds across the lake. The "lake effect" also routinely causes Michigan’s Upper Peninsula to be buried in 6 times more snow than downtown Duluth during winters.

During autumns, the dangerous "Gales of November" can occur, created by low-pressure systems that pass across the lakes. Wind speeds can reach 50 mph (80 kph), and gusts can exceed 100 mph (160 kph). Duluth is hidden under a heavy fog blanket for an average of 52 days each year.

Islands and Lakes

The state of Michigan is the home of the largest island on Lake Superior, called Isle Royale (535 sq kilometers in area, or 207 square miles). The island itself is home to several lakes, among which the largest is Siskiwit Lake, approximately 9 kilometers in length and 17 sq km in surface area. Siskiwit Lake but also other lakes on Isle Royale are home to islands themselves.

Other noteworthy islands include Madeline Island in Wisconsin (approximately 20 kilometers in length), Michipicoten Island in the Canadian province of Ontario (27 kilometers in length and 184 square kilometers in area), and Michigan’s Grand Island (12 kilometers in length).


Some of the largest cities located on the shores of Lake Superior are Duluth (Minnesota), Superior (Wisconsin), Thunder Bay (Ontario), Marquette (Michigan), and the twin cities of Sault Ste. Marie in Michigan and Sault Ste. Marie in Ontario. Duluth, on Lake Superior’s western tip, is the most inland port in the world.


Lake Superior has no shortage of amazing places to see. Some of them include the Isle Royale National Park, the Apostle Islands National Lakeshore, Pukaskwa National Park, Porcupine Mountains Wilderness State Park, Lake Superior Provincial Park, Sleeping Giant (Ontario) Grand Island National Recreation Area, Pictured Rocks National Lakeshore, and more. To aid in sightseeing and visiting all these incredible places, the Great Lakes Circle Tour was created. It is a scenic road system that connects all the Great Lakes and the St. Lawrence River.

So it’s easy to understand why tourism is one of the most important activities in the Lake Superior region, which is home to more than 600,000 people. There are many festivals, events, concerts going on which create a cheerful atmosphere.

During summer, some of the most popular activities include camping, sightseeing, boating, kayaking, fishing, and swimming. It’s important to note that the lake has rip currents that can be dangerous to swimmers, so beachgoers should know how to escape rip currents that can form along the lake’s shores. The lake is also remarkably clean and is popular among scuba divers, many of whom go for the sunken ships.

During winter the most important activities include skiing and ice fishing. In the years that have enough ice cover, the Bayfield Sea Caves located near Wisconsin’s Apostle Islands are well worth the trek. It’s important to note that recreationists should dress and behave to avoid hypothermia, especially those who go to the lake in winter.

Surrounded by Rocks Almost as Old as the Earth

The rocks at Lake Superior’s northern shore are almost as old as the Earth itself. The granites of the Canadian Shield were created in the Precambrian, sometime between 4.5 billion and 540 million years ago, by magma that forced its way to the surface. The ancient granite stones are still visible today.

The region that surrounds the lake is also well-known for the fact that it’s rich in minerals like iron, copper, silver, nickel, gold, and more. Some of the mines around the lake include the copper mine at Point Mamainse, the gold mine near Marathon, the silver mine at Silver Islet and the uranium mine at Theano Point.

Layers of sediments were deposited as the mountains eroded, sediments which ultimately became dolostone, limestone, the shale at Kakabeka Falls and taconite. The lake is located in a long-extinct rift valley, called the the Midcontinent Rift, which created cavities where amethyst can be found. The black basalt rock of St. Ignace Island, Michipicoten Island and Black Bay Peninsula was formed when lava erupted from the rift.

The region was covered by a sheet of ice 2 kilometers (1.25 miles) thick 10,000 years ago, during the Wisconsin glaciation. The retreat of the ice left deposits of sand, gravel, clay and boulders. As glacial meltwater accumulated in the basin, they formed Lake Minong, which was Lake Superior’s precursor.


As expected, the first people came here 10,000 years ago when the glaciers of the last Ice Age retreated. Those people are known under the name of Plano, and they used to hunt caribou on the northwestern shores of Lake Minong by using stone-tipped spears.

The ancestors of the Ojibwe and Cree people were the next documented here, and are known as the Shield Archaic. They lived between 5000 and 500 BC and they hunted, fished, used canoes, bows and mined copper in order to manufacture weapons and tools. They also established trading networks.

From 500 BC to 500 AD the Laurel people lived here, who developed net fishing. Later, between 900 and 1650 AD, the Terminal Woodland Indians made this region their home. They used birch bark canoes and snow shoes.

Of course, Lake Superior’s history would not be complete without mentioning the Anishinaabe people, which includes the Ojibwe or Chippewa. They inhabited the lake’s region for 500 years and called the lake Ojibwe Gichigami. When Europeans arrived, the Anishinaabe established themselves as middle-men between the French and other peoples from the region. Soon enough, they became the most important Indian nation, forcing the Sioux and Fox out. By the middle of the 18th century, they were already occupying all of Lake Superior’s shores.

The 18th century was marked by a booming fur industry. The most important companies were the Hudson's Bay Company, which had the monopoly, and the competing North West Company. However, by 1821 they had merged under the Hudson's Bay Company name.

Today, many of the cities and towns around the lake are engaged in mining activities. The pristine wilderness with its rugged landscape has also led to a significant increase in tourism, which is an important industry in the area nowadays.


Lake Superior has been and still is a very important shipping link in the Great Lakes Waterway. Lake freighters or small ocean freighters transport iron ore, grain, and other mined or manufactured materials across the lake. Shipping can’t be conducted on the lake from mid-January to late March, because of ice. The exact dates vary from season to season and depend on several factors that influence the breaking of the ice.

The Port of Duluth-Superior, also known as the "Great Lakes Bulk Cargo Capital", handles approximately 1,000 ships each year, which makes it one of the busiest US inland ports. These 1,000 ships carry approximately 42 million tons, worth around $1.9 billion.

The largest ships are also known as the lakers, and are about 300 meters (1,000 feet) in length and 32 meters (105 feet) in width. The ocean-going ships are known as the salties.


All the intense shipping activity on the lake has taken its toll, and the southern shore between Whitefish Point and Grand Marais is known as the graveyard of the Great Lakes. The area around Whitefish Point is the area where the biggest number of ships have been lost. The Whitefish Point Underwater Preserve protects all the shipwrecks. Some of the most damaging storms are the Mataafa Storm in 1905 and the Great Lakes Storm in 1913.

On October 11th, 1907, a 130-meter or 420-foot ore carrier called Cyprus sunk in 140 meters of water during a storm, on her second voyage. There was only one survivor out of a crew of 23. The shipwreck was found in August 2007.

The largest loss of lives happened in 1918, when the last warships to sink in the Great Lakes vanished. The ships were 2 French minesweepers called Inkerman and Cerisoles, and they sank in a Lake Superior storm, claiming 78 lives.

The last major shipwreck on Lake Superior is SS Edmund Fitzgerald, which sank 28 kilometers (17 miles) from Whitefish Point during a storm on November 10th, 1975. All 29 crew members died, with no bodies ever being found. At 222 meters in length, the ship was the largest ever to sink in Lake Superior, and at its launch in 1958, it was also the largest ship on the Great Lakes.


Even though there are far fewer fish in Lake Superior than there are in the other Great Lakes, the lake still boasts over 80 species of fish. Some of the most important which are native to the lake include brook trout, banded killifish, burbot, bloater, lake sturgeon, cisco (or lake herring), lake trout, longnose sucker, lake whitefish, northern pike, muskellunge, rock bass, pumpkinseed, smallmouth bass, round whitefish, white sucker, walleye, chub and yellow perch.

Other fish species have been either accidentally or intentionally introduced into Lake Superior, some of which include brown trout, atlantic salmon, chinook salmon, coho salmon, pink salmon, carp, freshwater drum, rainbow trout, rainbow smelt, ruffe, round goby, white perch, and sea lamprey.

The most commercially-important species include cicoes, chubs, lake trout, lake whitefish, and rainbow smelt. The name of lake herring was given to the cisco by Scandinavian settlers, because of the fish’s resemblance to ocean herring. It is harvested for fillets and caviar and is a great source of omega-3 fatty acids. It is one of the favorites in local restaurants.

Lake Superior is an oligotrophic lake, and it’s less productive compared to the other Great Lakes in terms of fish populations. This is because the lake has comparatively fewer dissolved nutrients in its water. Overfishing is also a problem on the Great Lakes.

Lake whitefish can be found mostly along the South Shore, and live in deep waters. They are prized for their fillets. The lake trout nearly went extinct in the late 1060s, but it has since made an incredible recovery. This is greatly due to a joint effort made by Canada and the United States to control sea lampreys. The siscowet is the most abundant form of lake trout.

Lake Superior Map