Together they hold one-fifth of all the fresh surface water on Earth, stretch across eight states and a Canadian province, and behave more like inland seas than lakes. If you think you already know these waters, the facts about the Great Lakes collected here will still surprise you — from ghost ships preserved in icy depths to storms so fierce they earned their own names.
Whether you have swum in their chilly surf, driven their scenic shorelines, or never laid eyes on them, this guide walks you through the most fascinating stories these waters hold: their staggering size, how glaciers carved them, the shipwrecks they hide, the weather they create, and the wildlife they shelter.
Facts About the Great Lakes: Size That Defies Imagination
Start with the numbers, because the scale of the Great Lakes is genuinely hard to picture. The five lakes together cover about 94,250 square miles of surface water — roughly the size of the entire United Kingdom. They hold an estimated six quadrillion gallons of water. To put that in perspective, the lakes contain around 21 percent of the world’s fresh surface water and about 84 percent of North America’s.
Lake Superior alone is the largest freshwater lake in the world by surface area, at roughly 31,700 square miles. It is so large that it could swallow the other four Great Lakes and still have room to spare, and its shoreline touches Minnesota, Wisconsin, Michigan, and Ontario.
The lakes’ combined shoreline runs for more than 10,000 miles when you count every bay and island edge — longer than the entire U.S. Atlantic seaboard. Eight states border at least one of the lakes: Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, and New York. And here is one of the stranger truths about the Great Lakes: despite sitting hundreds of miles from any ocean, the lakes are deep enough and rough enough that the U.S. Coast Guard treats them like open seas, complete with gales, fog, and winter ice that can crush a hull.
Meet the Five: Superior, Michigan, Huron, Erie, and Ontario
American schoolchildren have long memorized the lakes with the acronym HOMES: Huron, Ontario, Michigan, Erie, Superior. Each one has a personality of its own.
Lake Superior is the giant — largest, deepest (1,333 feet at its lowest point), and coldest, with an average water temperature that rarely climbs out of the 40s even in summer. Its water is so cold and low in oxygen at depth that shipwrecks rest on its floor almost perfectly preserved, looking as though they sank last week instead of a century ago.
Lake Michigan is the only Great Lake located entirely within the United States, bordered by Michigan, Wisconsin, Illinois, and Indiana. It is the third largest of the five by surface area and home to beloved shoreline towns, the Sleeping Bear Dunes, and the car-free retreat of Mackinac Island.
Lake Huron is the second largest by surface area and boasts the longest shoreline of any Great Lake once you trace around its roughly 30,000 islands, including Georgian Bay. It holds Manitoulin Island, the largest freshwater island in the world.
Lake Erie is the shallowest of the five, with a maximum depth of about 210 feet. That shallowness makes it the warmest — and the most biologically productive, supporting a celebrated walleye fishery that draws anglers from across the country.
Lake Ontario is the smallest by surface area but considerably deeper than Erie, reaching 802 feet. It sits at the eastern end of the chain, and its outflow becomes the St. Lawrence River on the long journey to the Atlantic.
How the Great Lakes Were Carved by Ice
Some of the most dramatic chapters of Great Lakes history begin more than 10,000 years ago, when massive glaciers of the last Ice Age ground their way across the region. As the ice advanced and retreated over thousands of years, it gouged out deep basins in the bedrock. When the glaciers finally melted, meltwater filled those basins — and the Great Lakes were born.
The lakes are still changing today. The land beneath them is slowly rebounding upward after being compressed by the weight of mile-thick ice, a process geologists call isostatic rebound. And the entire system drains eastward: water flows from Superior through the St. Marys River into Huron and Michigan, then through the St. Clair and Detroit rivers into Erie, over Niagara Falls into Ontario, and finally out the St. Lawrence River to the Atlantic Ocean.
A drop of water entering Lake Superior takes roughly two centuries to work its way through the whole system to the sea — one of the quiet, poetic reminders of how vast and slow-moving this inland water world really is. Speaking of Niagara, the falls themselves were carved by this same glacial story, and if you love waterfall trivia you will enjoy our 15 Niagara Falls facts most Americans don’t know.
Shipwrecks and Shipping: Facts About the Great Lakes Maritime History
For more than 150 years, the Great Lakes have been one of the busiest inland shipping routes on the planet. Freighters haul iron ore from Minnesota’s Mesabi Range to steel mills, grain from the Midwest to the world, and limestone, coal, and cement between ports. The Soo Locks at Sault Ste. Marie lift giant “lakers” around the rapids between Superior and Huron, and thousands of vessel transits pass through them every shipping season.
But the same waters that built fortunes have claimed ships by the thousands. Historians estimate that more than 6,000 shipwrecks lie on the bottoms of the Great Lakes, lost to sudden gales, fog, ice, and fire over two centuries of navigation. Because the water is fresh and frigid, wooden hulls that would have rotted away in saltwater oceans survive here in remarkable condition, making the lakes a world-class destination for wreck divers.
The most famous loss is the Edmund Fitzgerald, a 729-foot ore carrier that vanished in a Lake Superior storm on November 10, 1975, with all 29 crew members. The sinking inspired Gordon Lightfoot’s haunting ballad “The Wreck of the Edmund Fitzgerald” and remains the largest ship ever lost on the Great Lakes. To this day, November gales on Superior are spoken of with special respect.
Weather Wonders: Storms, Ice, and Lake-Effect Snow
The Great Lakes do not just sit under the weather — they make their own. In autumn and winter, cold air sweeping across the relatively warm lake water picks up moisture and dumps it as intense, narrow bands of snow on the downwind shores. This “lake-effect snow” can bury lakeside towns under several feet in a single storm while places a few miles away see barely a flurry.
In winter, the lakes can freeze dramatically. During the polar vortex winter of 2014, ice covered more than 92 percent of the Great Lakes’ surface — one of the highest ice coverage levels ever recorded. When that much ice locks in, winter shipping shuts down entirely and Coast Guard icebreakers work around the clock to keep channels open.
The lakes have also produced some of the deadliest storms in American history. In November 1913, the “White Hurricane” — a blizzard with hurricane-force winds — struck the lakes without modern warning, sinking or wrecking around 19 ships and killing more than 250 sailors. It remains the worst natural disaster ever to strike the Great Lakes, and it led directly to improved storm forecasting for the region.
Wildlife and Nature: More Surprising Facts About the Great Lakes
Beneath the surface and along the shores, the Great Lakes support an extraordinary web of life — along with some cautionary tales about invasive species. The sea lamprey, an eel-like parasite that slipped into the upper lakes through shipping canals in the 1800s, devastated native lake trout populations before control programs beat it back. In the 1980s, zebra mussels arrived in ballast water from ocean-going ships and spread explosively, filtering the water so clear in places that it changed entire food webs.
On the brighter side, the lakes are home to the ancient lake sturgeon, a living fossil that has swum these waters since the time of the dinosaurs. Sturgeon can live more than a hundred years and grow over six feet long, and conservation programs are slowly rebuilding populations that were nearly wiped out by overfishing.
Isle Royale in Lake Superior hosts one of the most remarkable science stories in America: the longest-running predator-prey study in the world, tracking wolves and moose on the isolated island for more than six decades. Meanwhile, shoreline dunes, wetlands, and islands shelter nesting piping plovers, bald eagles, and migratory birds by the millions. For more freshwater beauty beyond the big five, see our roundup of the most beautiful lakes in the USA.
Lighthouses, Islands, and Legendary Lakeside Towns
No tour of the facts about the Great Lakes is complete without their human landmarks. Michigan alone has more lighthouses than any other U.S. state — well over a hundred — built to guide ships through treacherous straits and around rocky points. Many are now museums or bed-and-breakfasts, and lighthouse tours are a beloved Great Lakes tradition.
The islands are destinations in their own right. Mackinac Island, sitting in the straits between Michigan and Huron, has banned private motor vehicles since 1898 — visitors get around by horse, bicycle, or on foot. Manitoulin Island in Lake Huron is the largest freshwater island on Earth and home to more than a hundred inland lakes of its own. The Apostle Islands in Superior, with their sea caves and old-growth forest, draw kayakers from around the world.
On the mainland, the Pictured Rocks National Lakeshore in Michigan’s Upper Peninsula shows off 200-foot sandstone cliffs painted in mineral streaks of red, orange, and green, while Sleeping Bear Dunes offers towering freshwater dunes with sweeping views over Lake Michigan. And when summer arrives, the lakes’ sandy shores rival any ocean coast — check our guide to the best beaches in the USA for lakeside favorites.
10 Quick Facts About the Great Lakes to Impress Your Friends
- Lake Superior is the largest freshwater lake in the world by surface area.
- The five lakes hold about 21 percent of Earth’s fresh surface water.
- Lake Michigan is the only Great Lake entirely inside the United States.
- Manitoulin Island in Lake Huron is the world’s largest freshwater island.
- An estimated 6,000+ shipwrecks rest on the lakes’ floors.
- The lakes’ combined shoreline stretches more than 10,000 miles.
- Lake-effect snow can dump feet of snow on one town while nearby areas stay dry.
- In 2014, ice covered over 92 percent of the lakes — nearly the entire system.
- The Edmund Fitzgerald sank in Lake Superior on November 10, 1975.
- A drop of water takes about 200 years to travel from Lake Superior to the Atlantic.
From their glacial birth to their storm-tossed present, the Great Lakes remain one of America’s greatest natural wonders — five inland seas that shaped the nation’s industry, ecology, and imagination. These facts about the Great Lakes only scratch the surface of what makes them extraordinary, so pick a shoreline, plan a road trip, and experience them for yourself. Share this guide with a fellow lake lover, and tell us in the comments: which Great Lake is your favorite?