- Massachusetts, United States8
- Mazatlan, Mexico1
- Mediterranean2
- Mediterranean Sea3
- Michigan, United States1
- Mississippi Drainage8
- Mississippi, United States2
- Mohawk River, New York, United States1
- Mokelumne River, California, United States2
- Moluccas, Indonesia 1
- Mumbai, India1
- New Bedford, Bristol County, Massachusetts, United States1
- New England8
- New Jersey, United States2
- New York Bay1
- Nolichucky River, Tennessee, United States1
- Oaks Island, Waccamaw River, Georgetown County, South Carolina, United States1
- Ohio Drainage1
- Ohio River1
- Ohio River, Louisville, Jefferson County, Kentucky, United States2