The meridian 66° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Atlantic Ocean, the Caribbean Sea, South America, the Southern Ocean, and Antarctica to the South Pole. The 66th meridian west forms a great circle with the 114th meridian east.

From Pole to Pole

Starting at the North Pole and heading south to the South Pole, the 66th meridian west passes through: ! scope="col" width="120" | Co-ordinates ! scope="col" | Country, territory or sea ! scope="col" | Notes ! scope="row" style="background:#b0e0e6;" | Arctic Ocean ! scope="row" style="background:#b0e0e6;" | Lincoln Sea ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Nares Strait ! scope="row" | 🇬🇱 ! scope="row" style="background:#b0e0e6;" | Nares Strait ! scope="row" | 🇬🇱 ! scope="row" style="background:#b0e0e6;" | Baffin Bay ! scope="row" style="background:#b0e0e6;" | Davis Strait ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Davis Strait ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Frobisher Bay ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Hudson Strait ! scope="row" style="background:#b0e0e6;" | Ungava Bay ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Gulf of Saint Lawrence ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Chaleur Bay ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Bay of Fundy ! scope="row" | 🇨🇦 ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" | 🇵🇷 ! scope="row" style="background:#b0e0e6;" | Caribbean Sea ! scope="row" | 🇻🇪 ! scope="row" | 🇧🇷 ! scope="row" | 🇧🇴 ! scope="row" | 🇦🇷 ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" | 🇦🇷 ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" | 🇦🇷 ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" style="background:#b0e0e6;" | Southern Ocean ! scope="row" | Antarctica ! scope="row" style="background:#b0e0e6;" | Southern Ocean ! scope="row" | Antarctica