<P> The IDL circumscribes Kiribati by swinging far to the east, almost reaching the 150 ° W meridian . Kiribati's easternmost islands, the southern Line Islands south of Hawaii, have the most advanced time on Earth, UTC + 14 hours . South of Kiribati, the IDL returns westwards but remains east of 180 °, passing between Samoa and American Samoa . </P> <P> In much of this area, the IDL follows the 165 ° W meridian . Accordingly, Samoa, Tokelau, Wallis and Futuna, Fiji, Tonga, Tuvalu and New Zealand's Kermadec Islands and Chatham Islands are all west of the IDL and have the same date . American Samoa, the Cook Islands, Niue, and French Polynesia are east of the IDL and one day behind . </P> <P> The IDL then bends southwest to return to 180 ° . It follows that meridian until reaching Antarctica, which has multiple time zones . Conventionally, the IDL is not drawn into Antarctica on most maps . (See § Cartographic practice and convention below .) </P> <P> A person who goes around the world from east to west (the same direction as Magellan's voyage) would gain or set their clock back one hour for every 15 ° of longitude crossed, and would gain 24 hours for one circuit of the globe from east to west if they did not compensate by setting their clock forward one day when they crossed the IDL . In contrast, a west - to - east circumnavigation of the globe loses an hour for every 15 ° of longitude crossed but gains back a day when crossing the IDL . The IDL must therefore be observed in conjunction with the Earth's time zones: on crossing it in either direction, the calendar date is adjusted by one day . </P>

International date line on a flat world map