Ports starting from: O
- Oak Bluff
- Oakham Ness
- Oakland
- Oaxen
- Oban
- Obidos
- Ocean Cay
- Ocean Falls
- Ocho Rios
- Odda
- Odense
- Odessa
- Odudu Terminal
- Offshore Pascagoula No 2
- Ofunato
- Ogden Point
- Ogdensburg
- Ogishima
- Oguendjo Terminal
- Ohmans
- Oistins Bay Tanker Terminal
- Oita
- Okha
- Okkye
- Okono Terminal
- Okpo
- Okrika
- Oktyabrsk
- Olbia
- Old City Harbour-Port of Tallinn
- Old Kilpatrick
- Oldenburg
- Oldersum
- Oleum
- Olga
- Olongapo
- Oltenitza
- Olympia
- Omaezaki
- Omisalj
- Omishima
- Onahama
- Onega
- Onehunga
- Onne
- Onoda
- Onomichi
- Onsan
- Ontonagon
- Oporto
- Opua
- Oran
- Orange
- Oranjestad
- Ordu
- Orehoved
- Oristano
- Oritkari
- Orkanger
- Ormoc
- Ornskoldsvik
- Oro Bay
- Orrskar
- Orsova
- Orth
- Ortona
- Ortviken
- Osaka
- Oshawa
- Oskarshamn
- Oslo
- Ostend
- Ostermoor
- Ostrand
- Ostrica
- Oswego
- Otago Harbour
- Otaru
- Otranto
- Otterbacken
- Otterham
- Oulu
- Ovendo
- Owase
- Owen Sound
- Owendo
- Oxelosund
- Oxhaga Harbour
- Ozamiz
- Ozol