The meridian 178° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.
The 178th meridian west forms a great circle with the 2nd meridian east.
Starting at the North Pole and heading south to the South Pole, the 178th meridian west passes through:
| Co-ordinates | Country, territory or sea | Notes | |
|---|---|---|---|
| Arctic Ocean | |||
| Chukotka Autonomous Okrug — Wrangel Island | |||
| Chukchi Sea | |||
| Chukotka Autonomous Okrug | |||
| Bering Sea | |||
| Alaska — Tanaga Island | |||
| Pacific Ocean | Passing just east of Kure Atoll, Hawaii, (at) Passing just east of Futuna Island, (at) | ||
| Alofi Island | |||
| Pacific Ocean | Passing just east of Vatoa Island, (at) Passing just west of Raoul Island, (at) | ||
| Southern Ocean | |||
| Antarctica | Ross Dependency, claimed by |