According to Wikipedia, the source for everything:
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron.
After a lot of driving we are happy to spend two days here at a beautiful beach town on Lake Michigan. We are all enjoying the beach with it’s warm fresh water – perfect for swimming on these hot humid days. Our friend Amy is hosting us at her spacious and comfortable lake house just 5 minutes walk from the private beach (local residents allowed only).