International Date Line (Lose Day) Port Summary
The international date line, established in 1884, passes through the mid-Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth. It is located halfway around the world from the prime meridian — the 0 degrees longitude line in Greenwich, England.
The international date line functions as a “line of demarcation” separating two consecutive calendar dates. When you cross the date line, you become a time traveler of sorts! Cross to the west and it’s one day later; cross back and you’ve “gone back in time."
Despite its name, the international date line has no legal international status and countries are free to choose the dates that they observe. While the date line generally runs north to south from pole to pole, it zigzags around political borders such as eastern Russia and Alaska’s Aleutian Islands.
The IDL is on the opposite side of the Earth to the Prime Meridian. The Prime Meridian is used to define Universal Time and is the meridian from which all other time zones are calculated. Time zones to the east of the Prime Meridian are in advance of UTC (up to UTC+14); time zones to the west are behind UTC (to UTC-12). The IDL and the moving point of midnight separate the two calendar days that are current somewhere on Earth. A traveller crossing the IDL eastbound subtracts one day, or 24 hours, so that the calendar date to the west of the line is repeated after the following midnight. Crossing the IDL westbound results in 24 hours being added, advancing the calendar date by one day. The IDL is necessary to have a fixed, albeit arbitrary, boundary on the globe where the calendar date advances in the westbound direction.For additional information please visit the International Date Line (Lose Day) website.
View detailed past and future International Date Line (Lose Day) visit history.
15-Night South Pacific Cruise from Honolulu ending in Sydney
13-Night South Pacific Cruise from Honolulu to Sydney