The Great Lakes — Erie, Huron, Michigan, Ontario, and Superior — hold one-fifth of all the fresh water on the Earth’s surface. Their combined coastline extends for over 10,000 miles. Each year, they attract several million tourists from the U.S. and around the world. But those facts are pretty basic. Whether it’s pirates, shipwrecks, or Babe Ruth’s first official home run, these fascinating tidbits are a bit less straightforward.

Lake Michigan once had pirates

Forget the Pirates of the Caribbean: The Great Lakes had their own share of buccaneers who patrolled the dangerous waters and terrorized the lake traffic, mainly in the mid-1800s into the early 1900s. But instead of gold, lumber and alcohol were the main prizes to be won. One of the more famous characters was “King” James Jesse Strang, a self-proclaimed religious leader (and looter). “Roaring” Dan Seavey was another — the only one to actually face charges of piracy on the Great Lakes. The former Navy sailor set false lights along the coastline, lured ships to their doom, and plundered the wreckage. Fortunately for locals, as the population along the Great Lakes grew in the 20th century, the pirate problems on the Great Lakes eventually faded away.

Lake Superior has a shipwreck museum

Forget the Pirates of the Caribbean: The Great Lakes had their own share of buccaneers who patrolled the dangerous waters and terrorized the lake traffic, mainly in the mid-1800s into the early 1900s. But instead of gold, lumber and alcohol were the main prizes to be won. One of the more famous characters was “King” James Jesse Strang, a self-proclaimed religious leader (and looter)

. “Roaring” Dan Seavey was another — the only one to actually face charges of piracy on the Great Lakes. The former Navy sailor set false lights along the coastline, lured ships to their doom, and plundered the wreckage. Fortunately for locals, as the population along the Great Lakes grew in the 20th century, the pirate problems on the Great Lakes eventually faded away.

The lakes have the world’s largest freshwater dune system

One of the reasons so many tourists flock to the Great Lakes each year is to enjoy an alternative to East and West Coast beaches — but the lakes' sandy shores are also home to a unique geological feature found on neither coast. The lakes boast the largest freshwater coastal dune system in the world. Lake Michigan alone is surrounded by more than 275,000 square acres of sand dunes. National and state parks — such as Sleeping Bear Dunes National Lakeshore and Pictured Rocks National Lakeshore — offer access to these magnificent dunes, which are perfect for hiking, sandcastle building, or simply laying back and enjoying the view.

The Great Lakes basin is home to nearly 35 million people

The Great Lakes hold about 84% of North America’s surface fresh water and thus play a vital role in the agricultural, power, and transportation industries. Some 34 million people live within the Great Lakes Basin, representing almost a third of the Canadian population and nearly 10% of the U.S. population. Together, the five lakes form a key part not just of North America’s cultural and geographic heritage, but also its technological and economic future.

Lake Superior might not be so superior

The largest of the Great Lakes, Lake Superiorcovers nearly 32,000 square miles and contains more water than the other four lakes combined. It’s often considered the largest freshwater lake in the world (the saltwater Caspian Sea is the largest overall). But since Lakes Michigan and Huron are connected by the four-mile-wide, 30-mile-long Straits of Mackinac, some scientists argue that they are in fact not two separate lakes but one larger body. If counted as one, Michigan-Huron would be larger than Lake Superior, pushing the latter into second place among the world’s largest freshwater lakes, and third place overall.

Only Lake Michigan is entirely within the U.S.

The Great Lakes border six Midwestern states — Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin — and two Canadian provinces, Ontario and Quebec. Lake Michigan is the only one of the Great Lakes that does not touch any Canadian territory. The lake’s name derives from the Ojibwa word mishigami, which means “large lake.” The state of Michigan was named after the lake, and it’s often nicknamed the “Great Lakes State” since it is the only state to touch four of the five lakes.

Geologically speaking the Great Lakes are quite young

Parts of Canada’s Hudson Bay are more than 4 billion years old. The Appalachian Mountainsformed 480 million years ago. But the Great Lakes? They’re geological babies. They were carved out by glaciers some 10,000 years ago. That’s not to say the rocks around them are young — some of the rocks on Michigan’s Upper Peninsula date back approximately 3.6 billion years. The area covered by the Great Lakes was once a series of glacial rifts; as the ice receded, the melt filled the basins, creating the lakes we know today.

There’s supposedly a Great Lakes monster

Every region has its mythical creatures, and the Great Lakes are no exception: Scotland has the Loch Ness Monster (nicknamed Nessie), and the Great Lakes have Bessie.  The 20-foot-long sea serpent reportedly lives in Lake Erie. Fishermen on the lake claimed to have first spotted her in the 1790s, and she made several more appearances in the 1980s. Bessie is not the only Great Lakes cryptid, however. Lake Superior has Pressie, also a sea serpent, while Lake Huron has Mishebeshu, a water lynx said to hunt children from beneath the ice. Also in Lake Huron is Saggy, a comparatively tame sea serpent who likes to rub against fishing boats.

There’s a Lake Michigan triangle

There's one part of Lake Michigan that is particularly treacherous for ships, so much so that it is often compared to the Bermuda Triangle. The Lake Michigan Triangle covers an area between Benton Harbor and Ludington in Michigan and Manitowoc, Wisconsin. Tales abound of ships that mysteriously disappeared, never to reach their destinations, and many still avoid the area out of superstition. To add to the mystery, divers have found underwater monuments the size of Stonehenge, complete with carvings of prehistoric creatures.

It’s a 6,500-mile drive around all of the lakes

To see as much as you can of the Great Lakes without actually stepping foot on a boat, consider the Circle Tour. In 1988, the Great Lakes Commission created a scenic driving route that encircles all five lakes, passing through eight states and Ontario. To complete the entire Circle Tour would mean driving a total of 6,500 miles, but you can break it into smaller chunks by choosing to circle just one of the lakes. If the Lake Superior tour (1,287 miles) seems a touch too long, try the routes around Lake Michigan or Erie, which are each closer to 600 miles. Just remember to allow plenty of time to get out and enjoy the view.

The world’s largest underground salt mine is beneath Lake Huron

What is now the Goderich Salt Mine was discovered by accident in 1866. A local flour mill owner was drilling for oil in the hope of striking it rich, and instead found rock salt, the first bed ever found in North America. Much of the mine is located some 1,800 feet below Lake Huron. That’s as deep as Toronto’s CN Tower is tall. The rock salt is shipped along the St. Lawrence Seaway before being distributed across the country for use in icy weather. It is now the world’s largest underground salt mine, covering an area of 2.7 million square miles.

Legend has it that Babe Ruth’s ball is in Lake Ontario

What is now the Goderich Salt Mine was discovered by accident in 1866. A local flour mill owner was drilling for oil in the hope of striking it rich, and instead found rock salt, the first bed ever found in North America. Much of the mine is located some 1,800 feet below Lake Huron. That’s as deep as Toronto’s CN Tower is tall. The rock salt is shipped along the St. Lawrence Seaway before being distributed across the country for use in icy weather. It is now the world’s largest underground salt mine, covering an area of 2.7 million square miles.