Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Old State Cemetery | Cemetery | 19 | Horry | 34 08 52 N | 079 10 11 W |
| Old Stone Cemetery | Cemetery | 243 | Pickens | 34 39 48 N | 082 48 55 W |
| Old Stone Church | Church | 249 | Oconee | 34 39 51 N | 082 48 55 W |
| Old Stone Church Cemetery | Cemetery | 137 | Fairfield | 34 23 24 N | 081 10 46 W |
| Old Storm Branch Baptist Church | Church | 54 | Aiken | 33 29 23 N | 081 54 27 W |
| Old Sweetwater Church | Church | 12 | Horry | 33 46 46 N | 079 01 25 W |
| Old Tabernacle Cemetery | Cemetery | 186 | Greenwood | 34 16 00 N | 082 11 02 W |
| Old Tenant Pond | Reservoir | 2 | Berkeley | 32 57 12 N | 079 58 57 W |
| Old Town | Populated Place | 3 | Charleston | 32 48 17 N | 079 59 04 W |
| Old Town Ferry (historical) | Crossing | 112 | Newberry | 34 09 53 N | 081 46 45 W |
| Old Towne Shopping Center | Locale | 311 | Greenville | 34 50 25 N | 082 21 25 W |
| Old Troy School (historical) | School | 155 | Greenwood | 33 59 23 N | 082 17 20 W |
| Old Union Cemetery | Cemetery | 57 | Orangeburg | 33 23 38 N | 081 03 48 W |
| Old Union Church (historical) | Church | 56 | Orangeburg | 33 23 37 N | 081 03 45 W |
| Old Vat (historical) | Populated Place | 9 | Berkeley | 32 55 55 N | 079 50 54 W |
| Old Waxhaw Church | Church | 190 | Lancaster | 34 47 20 N | 080 49 58 W |
| Old Way Pond | Reservoir | 69 | Calhoun | 33 38 25 N | 080 53 47 W |
| Old Whitetown Church (historical) | Church | 146 | McCormick | 33 52 44 N | 082 11 59 W |
| Old Willington Church (historical) | Church | 144 | McCormick | 33 57 16 N | 082 28 34 W |
| Old Wilson Church | Church | 196 | Chester | 34 38 49 N | 081 07 55 W |
| Old Womans Lake | Lake | 0 | Horry | 33 43 56 N | 079 02 58 W |
| Old Womans Point | Cape | 9 | Charleston | 32 47 01 N | 079 52 24 W |
| Old Zion Baptist Church | Church | 119 | Chester | 34 37 54 N | 081 18 32 W |
| Old Zion Cemetery | Cemetery | 186 | Abbeville | 34 11 48 N | 082 25 44 W |
| Old Zion Cemetery | Cemetery | 164 | Chester | 34 38 23 N | 081 16 46 W |
| Old Zion Church | Church | 58 | Sumter | 33 44 12 N | 080 31 42 W |
| Old Zion Hill Church | Church | 150 | Aiken | 33 34 55 N | 081 44 51 W |
| Oldfield Creek | Stream | | Colleton | 32 56 37 N | 080 48 02 W |
| Oldfield Plantation | Locale | 23 | Berkeley | 33 26 24 N | 079 58 24 W |
| Oldfield Plantation Cemetery | Cemetery | 24 | Berkeley | 33 26 22 N | 079 58 24 W |
| Oldfield School (historical) | School | 94 | Orangeburg | 33 27 49 N | 080 56 59 W |
| Oldtown (historical) | Populated Place | 114 | Newberry | 34 10 24 N | 081 46 54 W |
| Oldtown Creek | Stream | | Charleston | 32 47 56 N | 079 58 36 W |
| Oldwoods | Populated Place | 197 | York | 34 57 46 N | 081 04 10 W |
| Ole Salem Estates | Populated Place | 315 | Pickens | 34 54 44 N | 082 33 06 W |
| Olga (historical) | Populated Place | 328 | Pickens | 35 00 10 N | 082 33 30 W |
| Olin | Populated Place | 7 | Georgetown | 33 25 31 N | 079 27 54 W |
| Olin Hall | Building | 222 | Pickens | 34 40 39 N | 082 50 14 W |
| Olive Branch | Stream | | Charleston | 32 53 31 N | 080 06 57 W |
| Olive Branch Cemetery | Cemetery | 182 | Lexington | 33 54 02 N | 081 32 40 W |
| Olive Branch Church | Church | 13 | Charleston | 32 53 05 N | 080 07 44 W |
| Olive Grove Cemetery | Cemetery | 22 | Florence | 34 01 16 N | 079 43 17 W |
| Olive Grove Church | Church | 59 | Orangeburg | 33 30 14 N | 080 48 23 W |
| Olive Grove Church (historical) | Church | 22 | Florence | 34 01 16 N | 079 43 20 W |
| Olive Grove School | School | 22 | Florence | 34 01 36 N | 079 43 47 W |
| Olive Grove School | School | 57 | Orangeburg | 33 30 16 N | 080 48 21 W |
| Olive School (historical) | School | 150 | York | 34 51 32 N | 081 18 29 W |
| Oliver Church (historical) | Church | 187 | Chester | 34 38 11 N | 081 08 12 W |
| Oliver Crossroads | Populated Place | 32 | Dillon | 34 23 05 N | 079 15 49 W |
| Oliver Gospel Mission | Church | 93 | Richland | 34 00 22 N | 081 02 14 W |
| Oliver Mill (historical) | Locale | 103 | Chesterfield | 34 41 17 N | 080 14 02 W |
| Oliver Pond | Reservoir | 104 | Kershaw | 34 18 49 N | 080 43 59 W |
| Oliver Pond Dam D-2529 | Dam | 104 | Kershaw | 34 18 49 N | 080 43 59 W |
| Olivet Cemetery | Cemetery | 26 | Marion | 34 07 02 N | 079 17 44 W |
| Olivet Cemetery | Cemetery | 193 | York | 34 51 23 N | 081 15 09 W |
| Olympia | Populated Place | 55 | Richland | 33 58 36 N | 081 01 47 W |
| Olympia Cemetery | Cemetery | 53 | Richland | 33 58 20 N | 081 01 56 W |
| Olympia School | School | 54 | Richland | 33 58 38 N | 081 01 40 W |
| Omega School | School | 27 | Colleton | 32 55 43 N | 080 45 50 W |
| One of the Arrowhead Lakes | Reservoir | 130 | Edgefield | 33 37 36 N | 081 53 29 W |
| Oneal Pond Dam D-2568 | Dam | 33 | Allendale | 32 56 13 N | 081 16 11 W |
| Oneal School (historical) | School | 136 | Newberry | 34 07 16 N | 081 30 24 W |
| Oolenoy Cemetery | Cemetery | 319 | Pickens | 34 59 39 N | 082 38 30 W |
| Oolenoy Church | Church | 316 | Pickens | 34 59 43 N | 082 38 29 W |
| Oolenoy River | Stream | | Pickens | 35 00 30 N | 082 35 33 W |
| Oolenoy River WCD Dam Number 10 D-1949 | Dam | 342 | Pickens | 34 59 18 N | 082 44 29 W |
| Oolenoy River WCD Dam Number Nine D-1948 | Dam | 352 | Pickens | 34 59 30 N | 082 42 35 W |
| Oolenoy School (historical) | School | 307 | Pickens | 34 59 25 N | 082 38 34 W |
| Oolenoy Valley Airport | Airport | 312 | Pickens | 34 59 53 N | 082 44 05 W |
| Open Bay | Swamp | 29 | Florence | 33 58 17 N | 079 46 04 W |
| Open Bible Church (historical) | Church | 132 | Saluda | 34 02 53 N | 081 43 38 W |
| Open Door Church | Church | 238 | Cherokee | 35 02 27 N | 081 38 02 W |
| Open Door Church | Church | 10 | Horry | 33 51 40 N | 078 39 04 W |
| Opening Pond | Lake | 18 | Horry | 33 57 39 N | 078 57 58 W |
| Ophelias Dam | Dam | 139 | Union | 34 38 30 N | 081 26 35 W |
| Ophir Canal (historical) | Canal | 23 | Berkeley | 33 17 40 N | 080 05 28 W |
| Oponee Memorial Gardens | Cemetery | 289 | Oconee | 34 42 48 N | 083 00 08 W |
| Opossum Branch | Stream | | Fairfield | 34 25 28 N | 081 14 57 W |
| Opossum College (historical) | School | 73 | Barnwell | 33 17 35 N | 081 13 29 W |
| Opossum Creek | Stream | | Oconee | 34 45 27 N | 083 19 05 W |
| Opossum Point | Cape | 3 | Beaufort | 32 10 40 N | 080 46 53 W |
| Opossum Point Cemetery | Cemetery | 3 | Beaufort | 32 10 32 N | 080 45 58 W |
| Opossum Point Landing | Populated Place | 3 | Beaufort | 32 10 38 N | 080 46 22 W |
| Opportunity School | School | 81 | Lexington | 33 57 15 N | 081 06 42 W |
| Ora | Populated Place | 209 | Laurens | 34 34 54 N | 081 59 44 W |
| Ora Associate Reformed Presbyterian Church | Church | 207 | Laurens | 34 34 56 N | 081 59 42 W |
| Orange Grove | Populated Place | 3 | Beaufort | 32 24 02 N | 080 39 43 W |
| Orange Grove Cemetery | Cemetery | 4 | Beaufort | 32 21 36 N | 080 36 10 W |
| Orange Grove Church | Church | 50 | Bamberg | 33 12 60 N | 081 03 36 W |
| Orange Grove Church | Church | 3 | Beaufort | 32 22 01 N | 080 36 26 W |
| Orange Grove Elementary School | School | 6 | Charleston | 32 49 17 N | 080 00 04 W |
| Orange Grove Estates (subdivision) | Populated Place | 7 | Charleston | 32 49 04 N | 080 00 00 W |
| Orange Grove Plantation | Locale | 3 | Beaufort | 32 21 56 N | 080 36 24 W |
| Orange Grove Plaza Shopping Center | Locale | 5 | Charleston | 32 49 16 N | 079 59 34 W |
| Orange Hill Church | Church | 61 | Sumter | 33 51 53 N | 080 30 56 W |
| Orange Hill School | School | 60 | Sumter | 33 51 52 N | 080 30 54 W |
| Orange Hill School (historical) | School | 66 | Chesterfield | 34 44 49 N | 079 56 58 W |
| Orange Hill School (historical) | School | 61 | Sumter | 33 51 53 N | 080 30 57 W |
| Orangeburg | Populated Place | 74 | Orangeburg | 33 29 31 N | 080 51 20 W |
| Orangeburg City Hall | Building | 72 | Orangeburg | 33 29 19 N | 080 51 47 W |
| Orangeburg County | Civil | 52 | Orangeburg | 33 26 01 N | 080 45 59 W |
| Orangeburg County Courthouse | Building | 68 | Orangeburg | 33 29 32 N | 080 51 47 W |
| Orangeburg County Free Library | Building | 74 | Orangeburg | 33 29 31 N | 080 51 39 W |
| Orangeburg County Jail | Building | 75 | Orangeburg | 33 29 23 N | 080 51 43 W |
| Orangeburg Historic District | Park | 68 | Orangeburg | 33 29 32 N | 080 51 48 W |
| Orangeburg Lutheran Church | Church | 71 | Orangeburg | 33 29 57 N | 080 51 42 W |
| Orangeburg Mall Shopping Center | Locale | 82 | Orangeburg | 33 30 34 N | 080 51 49 W |
| Orangeburg Manor (subdivision) | Populated Place | 52 | Orangeburg | 33 28 41 N | 080 51 28 W |
| Orangeburg Municipal Airport | Airport | 57 | Orangeburg | 33 27 43 N | 080 51 28 W |
| Orangeburg National Fish Hatchery | Locale | 46 | Orangeburg | 33 24 33 N | 080 52 50 W |