Wisconsin lakes: O
99 lakes
- O'Brien LakeIron
- O'Day LakeOneida
- O'Leary LakeGrant
- O'Neil Creek Flowage Number OneChippewa
- O'Neil Creek Flowage Number TwoChippewa
- O'Neil Flowage 0.2Chippewa
- O'Neil Flowage 0.5Chippewa
- Oak LakeLincoln
- Oak LakeForest
- Oak LakeWashburn
- Oak LakeWashburn
- Oak LakeIron
- Oak LakeBurnett
- Oak Ridge LakeSt. Croix
- Oakwood LakeJackson
- Oatmeal LakeOneida
- Obadash LakeIron
- Oberlin LakeVilas
- Oconomowoc LakeWaukesha
- Oconomowoc Lake 87Waukesha
- Oconto Falls Pond 729Oconto
- Odd LakeChippewa
- Oesterle LakePortage
- Offers LakeWashburn
- Ogdensburg PondWaupaca
- Ogema MillpondPrice
- Ogle LakeMarquette
- Okauchee LakeWaukesha
- Okauchee Lake 85Waukesha
- Old Abe LakeChippewa
- Old Elk LakeDunn
- Old Mill PondBarron
- Old Taylor LakeWaupaca
- Old Veterans LakeMarinette
- Ole LakeOneida
- Ole LakeWashburn
- Ole LakeBayfield
- Ole LakeSawyer
- Ole LakeBayfield
- Oles LakePrice
- Oliver LakesChippewa
- Olivotti LakeLincoln
- Olson LakeFlorence
- Olson LakeBayfield
- Olson Meadows FlowageDouglas
- Omer LakePolk
- One Buck LakeDouglas
- One Island LakeLanglade
- One Man LakeIron
- One Mile LakeDouglas
- One Shoe LakeSawyer
- One Stone LakeOneida
- Oneida LakeOneida
- Oneonta LakeMarinette
- Onimish LakeForest
- Onland LakePortage
- Onsrud PondDane
- Orange MillpondJuneau
- Orienta Flowage (historical)Bayfield
- Oriole LakeIron
- Ormsby PondLanglade
- Orr LakePolk
- Oscar-Jenny LakeOneida
- Osceola LakePolk
- Osceola LakeVilas
- Osgood LakeSawyer
- Osprey LakeSawyer
- Osprey LakeWashburn
- Osseo Club PondTrempealeau
- Oswego LakeVilas
- Otis LakeGrant
- Ottawa LakeWaukesha
- Otter LakeWaupaca
- Otter LakeLincoln
- Otter LakeLanglade
- Otter LakeLanglade
- Otter LakeMarinette
- Otter LakeWashburn
- Otter LakeIron
- Otter LakeIron
- Otter LakeForest
- Otter LakeVilas
- Otter LakeChippewa
- Otter Lake 27Chippewa
- Otter PondSheboygan
- Ottman LakeWaupaca
- Our LakeBurnett
- Our LakeLanglade
- Overby LakeBayfield
- Owen Pond 5Clark
- Owl LakeIron
- Owl LakeBurnett
- Ox LakePolk
- Oxbo LakePrice
- Oxbow LakeIron
- Oxbow LakeVilas
- Oxbow LakeGogebic
- Oxbow PondJackson
- Oxford LakeMarquette