River with O
- Ohio river
- Oder
- Ottawa
- Oklahoma
- Oklahoma river
- Odra
- orinoco
- Orlando river
- Olga
- Obey river
- obed river
- Otay
- olive
- Otter Creek
- Olympus
- Otay River
- Oak Orchard River
- Osage
- ottawa river
- orion
- Orinoko
- Ottowa
- Orljava
- Omaha river
- Otto
- Owl
- Ovens
- Oka
- Onyx
- Oswego
- Obed
- Ocoee
- Olt
- oregan river
- oman river
- ophelia
- ozark
- One
- Ogden
- olympia
- Okavango
- Oker
- Oneida
- Onions
- only
- olivia
- oxe
- old
- omar
- Ouse river
- Ober
- Oise
- over
- olentangy
- Oil
- Ottowa River
- orwell
- oval river
- omaha
- OREGON
- Obion River
- ona
- Ostsee
- Okechobee
- owen
- osiris
- Okanogan
- orange county river
- oolong
- Olly
- olan
- Opera
- Oyster
The words in the list River with O come from players of the word game Categories game.