The meridian 21° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, the Atlantic Ocean, Europe, Africa, the Indian Ocean, the Southern Ocean, and Antarctica to the South Pole. The 21st meridian east forms a great circle with the 159th meridian west. Part of Namibia's border with Botswana is defined by the meridian.

From Pole to Pole

Starting at the North Pole and heading south to the South Pole, the 21st meridian east passes through: ! scope="col" width="125" | Co-ordinates ! scope="col" | Country, territory or sea ! scope="col" | Notes ! scope="row" style="background:#b0e0e6;" | Arctic Ocean ! scope="row" | 🇳🇴 ! scope="row" style="background:#b0e0e6;" | Arctic Ocean ! scope="row" | 🇳🇴 ! scope="row" style="background:#b0e0e6;" | Barents Sea ! scope="row" | 🇳🇴 ! scope="row" style="background:#b0e0e6;" | Barents Sea ! scope="row" | 🇳🇴 ! scope="row" style="background:#b0e0e6;" | Barents Sea ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" | 🇳🇴 ! scope="row" | 🇫🇮 ! scope="row" | 🇸🇪 ! scope="row" style="background:#b0e0e6;" | Baltic Sea ! scope="row" | 🇦🇽 ! scope="row" style="background:#b0e0e6;" | Baltic Sea ! scope="row" | 🇱🇻 ! scope="row" style="background:#b0e0e6;" | Baltic Sea ! scope="row" | 🇱🇹 ! scope="row" style="background:#b0e0e6;" | Curonian Lagoon ! scope="row" | 🇷🇺 ! scope="row" | 🇵🇱 ! scope="row" | 🇸🇰 ! scope="row" | 🇭🇺 ! scope="row" | 🇷🇴 ! scope="row" | 🇷🇸 ! scope="row" | Kosovo or 🇷🇸 ! scope="row" | ! scope="row" style="background:#b0e0e6;" | Lake Prespa ! scope="row" | 🇬🇷 ! scope="row" | 🇦🇱 ! scope="row" | 🇬🇷 ! scope="row" style="background:#b0e0e6;" | Mediterranean Sea ! scope="row" | 🇬🇷 ! scope="row" style="background:#b0e0e6;" | Mediterranean Sea ! scope="row" | 🇱🇾 ! scope="row" | 🇹🇩 ! scope="row" | 🇨🇫 ! scope="row" | 🇨🇩 ! scope="row" | ! scope="row" | 🇳🇦 ! scope="row" | 🇳🇦 / 🇧🇼 border ! scope="row" | 🇧🇼 ! scope="row" | 🇿🇦 ! scope="row" style="background:#b0e0e6;" | Indian Ocean ! scope="row" style="background:#b0e0e6;" | Southern Ocean ! scope="row" | Antarctica