- Malacca, Malaysia1
- Manila, Philippines2
- Manilla, Philippines1
- Martinique3
- Massachusetts, United States8
- Mazatlan, Mexico1
- Mediterranean2
- Mediterranean Sea3
- Meigs County, Portland, Ohio, United States1
- Michigan, United States1
- Mississippi Drainage8
- Mississippi, United States4
- 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