Are the Great Lakes Really Inland Seas?

By Gemma Tarlach.

Well, yes. And no. Actually, it depends on where you stand, in more ways than one.

the water reared  slammed onto the sand like an ambush predator. Then it withdrew, and came back. Again and again the surf attacked the beach, and exploded over a nearby concrete breakwater. White gulls stood out against a dull sky as they fought to stay aloft in winds that had gathered strength over hundreds of miles of open water. The National Weather Service had issued a gale warning, an alert used only for marine locations. But this wind advisory wasn’t for the coast along Cape Cod or California, and the spray from the angry surf wasn’t salty. This stormy seaside scene unfolded on a spring day along the shores of a mere lake, far from the nearest ocean.

The Great Lakes of North America’s midsection—Superior, Michigan, Huron, Erie, and Ontario—together span nearly 100,000 square miles, with a combined coastline just shy of 10,000 miles. They hold more than a fifth of Earth’s unfrozen fresh water, straddle an international border, and help move more than $15 billion dollars worth of cargo each year. They even have their own U.S. Coast Guard district, the only lakes with such a distinction. And the Guard’s rescue teams stay busy: Superior and its siblings are capable of storm surges, rip currents, tsunamis, rogue waves, unique extreme weather phenomena, and destructive surf. They have claimed more than 6,000 ships, more than the Gulf of Mexico and the Black Sea combined, according to estimates. So should we really be calling them the Great Inland Seas?

“The most accurate answer you’re going to get is, ‘I don’t know,’” says John Richard Saylor, author of the upcoming Lakes: Their Birth, Life, and Death. “I do think it comes down to semantics, what you want to call a ‘sea.’”