- Mediterranean1
- Mexico1
- Middletown, Middlesex County, Connecticut, United States1
- Mississippi Drainage1
- Moluccas, Indonesia 1
- Mount Vesuvius, Napoli, Campania, Italy1
- New England1
- Ohio River1
- Ohio River, Louisville, Jefferson County, Kentucky, United States1
- Ohio River, United States1
- Oregon, United States1
- Perkiomen, Montgomery County, Pennsylvania, United States1
- Red Sea1
- Redding (Reading), Fairfield County, Connecticut, United States1
- Rhode Island, United States1
- Richmond, Virginia, United States1
- Rogers Rock, Lake George, Hague, Warren County, New York, United States1
- Sapidum, Harford County, Maryland, United States1
- Saxony, Germany1
- Scarborough, North Yorkshire, England, United Kingdom1