A view of a beack at the International Dateline

Cross International Dateline

Travelers flying or cruising across the Pacific Ocean get to experience the only-one-place-in-the-world feeling of adding or losing a day within the span of a second. The International Date Line is the longitudinal boundary between where one day starts (to the west) and another day ends (to the east). It runs roughly along the 180th meridian of longitude in the middle of the ocean—with some exceptions in the southern Pacific, where sovereign islands opted for one side over the other for commercial reasons. The Date Line was initially proposed by astronomers from 25 countries at a conference in 1884, but took until the early 1900s to become standardized globally. After a few adjustments, the position of the Date Line was formalized in 1921.