International Date Line International Date Line The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups. The IDL is roughly based on the meridian of 180° longitude, roughly down the middle of the Pacific Ocean, and halfway around the world from the Greenwich meridian. In many places, the IDL follows
Comox Land District along that longitude to 49 degrees 39 minutes 15 seconds north latitude. From there, a short distance east to 124 degrees 59 minutes 51 seconds west longitude, and south along that longitude to 49 degrees 39 minutes north latitude, and 124 degrees 58 minutes 31 seconds west longitude, north along that longitude to 49 degrees 39 minutes 10 seconds north latitude at 124 degrees and east along that latitude to 124 degrees 57 minutes 45 seconds west longitude, following that longitude south to 49 degrees 38 minutes 50 seconds north longitude to 124 west 57 minutes 5 seconds west longitude