The meridian 121° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, the Indian Ocean, Australia, the Southern Ocean, and Antarctica to the South Pole. The 121st meridian east forms a great circle with the 59th meridian west.

From Pole to Pole

Starting at the North Pole and heading south to the South Pole, the 121st meridian east passes through: ! scope="col" width="130" | Co-ordinates ! scope="col" | Country, territory or sea ! scope="col" | Notes ! scope="row" style="background:#b0e0e6;" | Arctic Ocean ! scope="row" style="background:#b0e0e6;" | Laptev Sea ! scope="row" | 🇷🇺 ! scope="row" | ! scope="row" style="background:#b0e0e6;" | Yellow Sea ! scope="row" | ! scope="row" style="background:#b0e0e6;" | Yellow Sea ! scope="row" style="background:#b0e0e6;" | East China Sea ! scope="row" | ! scope="row" style="background:#b0e0e6;" | Hangzhou Bay ! scope="row" | ! scope="row" style="background:#b0e0e6;" | East China Sea ! scope="row" style="background:#b0e0e6;" | Taiwan Strait ! scope="row" | ! scope="row" style="background:#b0e0e6;" | Pacific Ocean ! scope="row" style="background:#b0e0e6;" | South China Sea ! scope="row" | 𝜙 ! scope="row" style="background:#b0e0e6;" | Isla Verde Passage ! scope="row" | 𝜙 ! scope="row" style="background:#b0e0e6;" | Sulu Sea ! scope="row" | 𝜙 ! scope="row" style="background:#b0e0e6;" | Celebes Sea ! scope="row" | 🇮🇩 ! scope="row" style="background:#b0e0e6;" | Gulf of Tomini ! scope="row" | 🇮🇩 ! scope="row" style="background:#b0e0e6;" | Gulf of Boni ! scope="row" | 🇮🇩 ! scope="row" style="background:#b0e0e6;" | Gulf of Boni ! scope="row" style="background:#b0e0e6;" | Banda Sea ! scope="row" | 🇮🇩 ! scope="row" style="background:#b0e0e6;" | Flores Sea ! scope="row" | 🇮🇩 ! scope="row" style="background:#b0e0e6;" | Savu Sea ! scope="row" style="background:#b0e0e6;" | Indian Ocean ! scope="row" | 🇦🇺 ! scope="row" style="background:#b0e0e6;" | Indian Ocean ! scope="row" style="background:#b0e0e6;" | Southern Ocean ! scope="row" | Antarctica