- Oak Hill
- Ogren
- Ouellette
- Outer Birch Island
- Outer Green Island
- Outer Green Island
- Outer Spectacle Island
- Outer Twin Island
- Oak Hill
- Oak Island
- Oak Knoll Island
- Oakdale
- Obeds Rock
- Outer Doctor Island
- Outer Island
- Overset Island
- Overlake
- Oak Hill
- Oceanville
- Old Soaker
- Opechee Island
- Orono Island
- Otter Creek
- Outer Bar Island
- Oak Hill
- Oar Island
- Ocean Point
- Orffs Corner
- Outer Heron Island
- Outer Island