The meridian 51° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Greenland, the Atlantic Ocean, South America, the Southern Ocean, and Antarctica to the South Pole.
The 51st meridian west forms a great circle with the 129th meridian east.
Starting at the North Pole and heading south to the South Pole, the 51st meridian west passes through:
| Co-ordinates | Country, territory or sea | Notes |
|---|---|---|
| Arctic Ocean | ||
| Lincoln Sea | ||
| Wulff Land | ||
| Sherard Osborn Fjord | ||
| Passing through several fjords, the Nuussuaq Peninsula and Alluttoq Island | ||
| Disko Bay | ||
| Passing through several fjords | ||
| Atlantic Ocean | ||
| Amapá Pará — from, passing through several islands in the mouth of the Amazon River Mato Grosso — from Goiás — from Mato Grosso do Sul — from Minas Gerais — from São Paulo — from Paraná — from Santa Catarina — from Rio Grande do Sul — from, passing through Lagoa dos Patos | ||
| Atlantic Ocean | ||
| Southern Ocean | ||
| Antarctica | Claimed by both (Argentine Antarctica) and (British Antarctic Territory) | |