O
- Oak Bay (Turkey Head) - Breakwater
- Oak Point Lighthouse
- Oakville Lighthouse
- Ocean Falls
- Ochre Pit Cove
- Oderin
- O'donnells
- Offer Wadham Island Lighthouse
- Ogden Island Range Lighthouse
- Ogden Point Lighthouse
- Oka
- Oka Sur Le Lac
- Okeover Inlet
- Old Bonaventure
- Old Cape Spear Lighthouse
- Old Channel Lighthouse
- Old Fort Bay-Quai Des Pêcheurs
- Old-Harry
- Old House Rock (St. Pauls)
- Old Pelee Passage Lighthouse
- Old Perlican
- Old Shop
- Old Town of Lunenburg
- Oliphant
- Ontario Mirror Dinghy Association
- Ontario Sailing Association
- Oona River
- Oona River - Mooring Buoys
- Open Hall
- Opitsat
- Oshawa
- Otter Island Lighthouse
- Ouellette Rapids (French River)
- Owen Sound-Marina
- Owen Sound Marina Lighthouse
- Owls Head
- Owls Head Lighthouse
