Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Osma Lake | Lake | 2337 | El Dorado | 38 50 17 N | 120 08 08 W |
| Oso Butte | Summit | 1606 | Siskiyou | 41 27 07 N | 121 48 04 W |
| Oso Canyon | Valley | | Los Angeles | 34 48 15 N | 118 43 46 W |
| Oso Canyon | Valley | | Santa Barbara | 34 32 43 N | 119 46 33 W |
| Oso Creek | Stream | | Orange | 33 31 10 N | 117 40 19 W |
| Oso Creek | Stream | | San Luis Obispo | 35 10 28 N | 120 16 50 W |
| Oso Creek | Stream | | Stanislaus | 37 17 48 N | 121 10 10 W |
| Oso Creek Dam | Reservoir | 266 | Orange | 33 39 30 N | 117 37 51 W |
| Oso Flaco Creek | Stream | | San Luis Obispo | 35 01 54 N | 120 38 02 W |
| Oso Flaco Lake | Lake | 5 | San Luis Obispo | 35 01 46 N | 120 37 19 W |
| Oso Pumping Plant | Locale | 957 | Los Angeles | 34 48 37 N | 118 43 10 W |
| Oso Spring | Spring | 1888 | El Dorado | 38 43 37 N | 120 17 16 W |
| Oso-Lobo Campground | Locale | 2000 | San Bernardino | 34 10 33 N | 116 51 41 W |
| Ospital Ranch | Locale | 91 | Calaveras | 38 07 24 N | 120 56 46 W |
| Osprey Information Center | Building | 731 | Trinity | 40 50 42 N | 122 51 33 W |
| Osprey Lake | Lake | 2208 | Siskiyou | 41 29 46 N | 123 07 46 W |
| Osprey Management Area | Locale | 1565 | Lassen | 40 36 56 N | 120 46 37 W |
| Osprey Point | Cape | 1 | San Diego | 32 44 10 N | 117 15 22 W |
| Ossagon Creek | Stream | | Humboldt | 41 26 31 N | 124 03 50 W |
| Osser Creek | Stream | | Sonoma | 38 46 57 N | 123 18 49 W |
| Oster Elementary School | School | 67 | Santa Clara | 37 15 22 N | 121 55 12 W |
| Osterried Gulch | Valley | | Siskiyou | 41 17 37 N | 122 51 55 W |
| Ostrander Lake | Lake | 2593 | Mariposa | 37 37 28 N | 119 33 02 W |
| Ostrander Park | Park | 103 | Alameda | 37 50 33 N | 122 14 04 W |
| Ostrander Rocks | Summit | 2467 | Mariposa | 37 41 23 N | 119 35 37 W |
| Ostrom | Populated Place | 21 | Yuba | 39 04 10 N | 121 30 42 W |
| Ostrom Point | Summit | 1405 | Modoc | 41 21 42 N | 121 07 06 W |
| Osuna Valley | Valley | | San Diego | 32 59 43 N | 117 12 22 W |
| Oswald | Populated Place | 15 | Sutter | 39 04 09 N | 121 37 34 W |
| Oswell Park | Park | 123 | Kern | 35 21 21 N | 118 56 38 W |
| Otay | Civil | 150 | San Diego | 32 37 17 N | 116 55 29 W |
| Otay | Civil | 193 | San Diego | 32 38 24 N | 116 56 15 W |
| Otay | Civil | 175 | San Diego | 32 36 29 N | 116 58 26 W |
| Otay | Populated Place | 18 | San Diego | 32 35 41 N | 117 03 52 W |
| Otay County Open Space Preserve | Park | 243 | San Diego | 32 36 49 N | 116 54 50 W |
| Otay Elementary School | School | 29 | San Diego | 32 35 47 N | 117 03 26 W |
| Otay la Mesa Business Center | Locale | 149 | San Diego | 32 33 58 N | 116 57 50 W |
| Otay Lake County Park | Park | 148 | San Diego | 32 36 23 N | 116 55 49 W |
| Otay Mesa | Summit | 189 | San Diego | 32 33 36 N | 116 56 10 W |
| Otay Mesa (subdivision) | Populated Place | 61 | San Diego | 32 34 24 N | 117 03 15 W |
| Otay Mesa Branch San Diego Public Library | Building | 36 | San Diego | 32 34 36 N | 117 04 06 W |
| Otay Mesa Industrial Park | Locale | 150 | San Diego | 32 34 10 N | 116 57 35 W |
| Otay Mesa International Center | Locale | 169 | San Diego | 32 33 30 N | 116 56 33 W |
| Otay Mountain | Summit | 1075 | San Diego | 32 35 41 N | 116 50 38 W |
| Otay Mountain Truck Trail | Trail | 846 | San Diego | 32 34 48 N | 116 51 05 W |
| Otay Mountain Wilderness | Reserve | 906 | San Diego | 32 35 42 N | 116 50 20 W |
| Otay Park | Park | 31 | San Diego | 32 35 50 N | 117 03 26 W |
| Otay Ranch | Locale | 149 | San Diego | 32 37 00 N | 116 59 07 W |
| Otay River | Stream | | San Diego | 32 36 23 N | 117 06 59 W |
| Otay River Marsh | Swamp | 4 | San Diego | 32 35 35 N | 117 05 42 W |
| Otay Valley | Valley | | San Diego | 32 35 30 N | 117 05 03 W |
| Otey Island | Island | 1265 | Siskiyou | 41 59 43 N | 121 50 18 W |
| Otey Ridge | Ridge | 1324 | Siskiyou | 41 59 18 N | 121 53 23 W |
| Oteys Sierra Village | Populated Place | 1357 | Inyo | 37 21 31 N | 118 27 33 W |
| Otis Art Institute | School | 79 | Los Angeles | 34 03 29 N | 118 16 36 W |
| Otis Canyon | Valley | | Lassen | 40 08 06 N | 120 16 22 W |
| Otis Canyon | Valley | | Santa Clara | 37 08 18 N | 121 33 51 W |
| Otis R Johnson Park | Park | 26 | Mendocino | 39 26 41 N | 123 47 39 W |
| Otis Ranch (historical) | Locale | 1496 | Plumas | 39 47 37 N | 120 33 03 W |
| Otis Roper Park | Park | 1230 | Siskiyou | 41 57 25 N | 121 28 48 W |
| Otis Spring | Spring | 1942 | Plumas | 40 06 54 N | 120 17 02 W |
| Otter Bar | Bar | 293 | Tuolumne | 38 06 33 N | 120 23 57 W |
| Otter Creek | Stream | | El Dorado | 38 57 25 N | 120 51 24 W |
| Otter Creek Elementary School | School | 538 | El Dorado | 38 59 38 N | 120 43 30 W |
| Otter Lake | Lake | 2716 | Tuolumne | 38 05 19 N | 119 39 20 W |
| Otterbein | Populated Place | 154 | Los Angeles | 33 59 15 N | 117 53 05 W |
| Ottley Gulch | Valley | | Siskiyou | 41 46 11 N | 123 20 11 W |
| Otto Center | Building | 91 | San Diego | 32 44 02 N | 117 08 54 W |
| Otto Mine | Mine | 421 | Lake | 38 42 13 N | 122 36 50 W |
| Otto Mine | Mine | 358 | San Bernardino | 35 16 24 N | 116 05 43 W |
| Otto Mountain | Summit | 518 | San Bernardino | 35 16 39 N | 116 05 54 W |
| Otto Square Shopping Center | Locale | 20 | San Diego | 32 41 49 N | 117 07 04 W |
| Ottoman Way Elementary School | School | 83 | Sacramento | 38 41 49 N | 121 11 59 W |
| Ottoway Creek | Stream | | Madera | 37 38 01 N | 119 27 10 W |
| Ottoway Lakes | Lake | 2950 | Madera | 37 38 30 N | 119 25 04 W |
| Ottoway Peak | Summit | 3501 | Madera | 37 38 32 N | 119 23 36 W |
| Oulton Point | Cape | 0 | Sacramento | 38 05 24 N | 121 38 12 W |
| Our House | Locale | 956 | Sierra | 39 25 03 N | 121 01 16 W |
| Our House Dam | Dam | 664 | Sierra | 39 24 43 N | 120 59 45 W |
| Our Lady and All Angels Catholic Church | Church | 237 | Ventura | 34 27 01 N | 119 13 34 W |
| Our Lady Help of Christians Church | Church | 95 | Los Angeles | 34 04 02 N | 118 13 04 W |
| Our Lady Help of Christians School | School | 96 | Los Angeles | 34 04 03 N | 118 13 03 W |
| Our Lady Help of Christians Valley Roman Catholic Church | Church | 27 | Santa Cruz | 36 56 28 N | 121 44 31 W |
| Our Lady of Angels Catholic Church | Church | 43 | San Diego | 32 42 45 N | 117 08 34 W |
| Our Lady of Angels Roman Catholic Church | Church | 8 | San Mateo | 37 35 09 N | 122 22 23 W |
| Our Lady of Angels School | School | 41 | San Diego | 32 42 42 N | 117 08 38 W |
| Our Lady of Angels School | School | 11 | San Mateo | 37 35 07 N | 122 22 20 W |
| Our Lady of Assumption School | School | 416 | San Bernardino | 34 10 20 N | 117 17 56 W |
| Our Lady of Assumption School | School | 39 | Ventura | 34 16 22 N | 119 15 13 W |
| Our Lady of Bright Mount Carmel Roman Catholic Church | Church | 62 | Los Angeles | 34 01 56 N | 118 19 19 W |
| Our Lady of Carmel Church | Church | 90 | Sonoma | 38 45 45 N | 122 58 40 W |
| Our Lady of Fatima Catholic Church | Church | 101 | Orange | 33 25 45 N | 117 36 33 W |
| Our Lady of Fatima Church | Church | 324 | San Bernardino | 34 07 05 N | 117 16 21 W |
| Our Lady of Fatima School | School | 15 | Los Angeles | 33 51 44 N | 118 04 47 W |
| Our Lady of Fatima School | School | 37 | Merced | 37 03 13 N | 120 51 18 W |
| Our Lady of Fatima School | School | 107 | Orange | 33 25 47 N | 117 36 31 W |
| Our Lady of Fatima School | School | 28 | Stanislaus | 37 40 04 N | 120 59 57 W |
| Our Lady of Fatima School (historical) | School | 10 | Sacramento | 38 36 28 N | 121 27 24 W |
| Our Lady of Good Counsel Roman Catholic Church | Church | 36 | Mendocino | 39 26 22 N | 123 47 54 W |
| Our Lady of Good Counsel School | School | 36 | Mendocino | 39 26 22 N | 123 47 54 W |
| Our Lady of Grace Church | Church | | Alameda | 37 42 05 N | 122 05 00 W |
| Our Lady of Grace Church | Church | 247 | Los Angeles | 34 09 39 N | 118 31 08 W |
| Our Lady of Grace School | School | 56 | Alameda | 37 42 02 N | 122 05 00 W |
| Our Lady of Grace School | School | 245 | Los Angeles | 34 09 43 N | 118 31 11 W |
| Our Lady of Grace School | School | 220 | San Diego | 32 48 12 N | 117 00 13 W |
| Our Lady of Grace School | School | 4 | Yolo | 38 32 53 N | 121 32 01 W |
| Our Lady of Guadalupe | School | 149 | Los Angeles | 34 05 11 N | 118 11 23 W |
| Our Lady of Guadalupe Academy | School | 276 | Riverside | 33 58 08 N | 117 22 00 W |
| Our Lady of Guadalupe Catholic Church | Church | -13 | Imperial | 32 47 22 N | 115 32 35 W |
| Our Lady of Guadalupe Catholic Church | Church | 131 | Los Angeles | 34 05 47 N | 117 56 00 W |