- Mark Island
- Mouse Island
- Moose Island
- Middle Hardwood Island
- Machias
- Machias Seal Island
- Machiasport
- Mackamp
- Mackerel Rock
- Mackworth Island
- MacMahan
- MacMahan Island
- MacQuillis Corner
- Macs Corner
- Macwahoc
- Macy
- Madawaska
- Madawaska
- Maddocks Corner
- Madison
- Madrid
- Madrid Junction
- Mahockanock Island
- Mahoney Island
- Maine
- Mainstream
- Major Island
- Malaga Island
- Malaga Island
- Malbons Mills