| Code | Country | Continent | Population |
| SEN | Senegal | Africa | 9,481,000 |
| SGP | Singapore | Asia | 3,567,000 |
| SHN | Saint Helena | Africa | 6,000 |
| SJM | Svalbard and Jan Mayen | Europe | 3,200 |
| SLB | Solomon Islands | Oceania | 444,000 |
| SLE | Sierra Leone | Africa | 4,854,000 |
| SLV | El Salvador | North America | 6,276,000 |
| SMR | San Marino | Europe | 27,000 |
| SOM | Somalia | Africa | 10,097,000 |
| SPM | Saint Pierre and Miquelon | North America | 7,000 |
| SSD | South Sudan | Africa | 12,340,000 |
| STP | Sao Tome and Principe | Africa | 147,000 |
| SUR | Suriname | South America | 417,000 |
| SVK | Slovakia | Europe | 5,398,700 |
| SVN | Slovenia | Europe | 1,987,800 |
| SWE | Sweden | Europe | 8,861,400 |
| SWZ | Swaziland | Africa | 1,008,000 |
| SYC | Seychelles | Africa | 77,000 |
| SYR | Syria | Asia | 16,125,000 |
| TCA | Turks and Caicos Islands | North America | 17,000 |