International Date Line Trivia
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45 free International Date Line trivia questions with answers — geography quiz, new questions added Sep 2026.
This International Date Line trivia quiz covers the imaginary boundary between one calendar day and the next, and the surprisingly long list of countries that have hopped across it. The easy questions ask which ocean it runs through, which line of longitude it roughly follows, what happens to the date when you cross it, and which country's islands see the New Year first. Then it works through the zigzags: the Diomedes, the Aleutians, the giant bulge around Kiribati and the gap between Samoa and American Samoa. The hard end is for people who enjoy calendar arithmetic: the Arab geographer who predicted the lost day, Magellan's crew discovering it at Cape Verde, the Philippines skipping 31 December 1844, Alaska's date jumping back at the 1867 handover, Samoa repeating the Fourth of July in 1892 and deleting a Friday in 2011, Kwajalein's Tuesday-to-Saturday work week, the two-hour window with three dates on Earth, and the fiction from Poe to Umberto Eco built on the paradox. Every answer was checked against the encyclopaedia entries on the International Date Line and the Diomede Islands before publishing, and the supporting sentence is stored with each question. Our time zones, Pacific islands and world geography quizzes are natural next stops.
30 of 45 questions with answers and explanations. Play the quiz
Q 01The International Date Line runs mostly through which ocean?
Pacific
Pacific: the line runs from pole to pole but mostly crosses the Pacific, which Magellan reportedly named 'peaceful' for the calm water he found after stormy seas.
Q 02Which line of longitude does the International Date Line roughly follow?
180°
180°, though the line zigzags east and west of that meridian so that island groups and territories each keep a single calendar date.
Q 03What happens to the calendar date when you cross the date line travelling eastbound?
It goes back one day
It goes back one day: an eastbound traveller turns the calendar back at the line and so lives through part of that date a second time.
Q 04Legally, what kind of line is the International Date Line?
A cartographic convention
A cartographic convention: no treaty or international body fixes the line, so the countries it passes near are free to choose which date they keep.
Q 05Travelling westward around the world, how must you set your clock for every 15° of longitude crossed?
Back one hour
Back one hour: solar noon shifts four minutes for every degree of longitude, so a place 15° farther west reaches noon an hour later.
Q 06The date line's first bend away from the meridian passes east of Wrangel Island and which Russian peninsula?
Chukchi
The line jogs east around the Chukchi Peninsula and Wrangel Island, keeping Chukotka and all of Russia on the Asian side of the date line.
Q 07Which unofficial US Navy title do sailors earn by crossing the date line?
Golden Dragon
Golden Dragon honors mark crossing the date line, and some sailors wear a golden dragon tattoo to show it; Shellbacks have crossed the equator.
Q 08Because of the date line, Big Diomede and Little Diomede are nicknamed what?
Tomorrow Island and Yesterday Island
Tomorrow Island and Yesterday Island: Russia's Big Diomede lies a day ahead, and after the Soviets built a base there its villagers were moved to the mainland, splitting families.
Q 09What has often joined Alaska's Little Diomede to Russia's Big Diomede across the date line?
A bridge of sea ice
A bridge of sea ice has usually formed between them in winter, and Little Diomede's villagers long ploughed a runway on the frozen sea for supply flights, until the ice grew too thin.
Q 10Which US island chain does the date line bend west to keep on the American date?
The Aleutian Islands
The Aleutian Islands arc west from the Alaska Peninsula to Attu, which Japanese troops seized in June 1942 before US forces won it back in May 1943.
Q 11Which two US islands, one of them Amelia Earhart's destination, are the last places to end each day?
Howland and Baker
Howland and Baker see each day out last; a runway was cleared on Howland for Earhart's 1937 refuelling stop, but she vanished on the way and never touched down.
Q 12Around which country does the date line swing far to the east, almost reaching 150°W?
Kiribati
Kiribati's president, Teburoro Tito, simply announced the change, and from 1 January 1995 the line has run along the country's many-cornered eastern boundary.
Q 13Which European country abstained from the 1884 International Meridian Conference's vote choosing the world's prime meridian?
France
Q 21When F-22 Raptors lost navigation at the date line in 2007, how did they get back to Hawaii?
Following their tanker planes
Following their tanker planes, the jets made it back to Hickam, and once the software was fixed they flew on to Kadena for their first overseas deployment.
Q 22When Samoa switched to the American date in 1892, which day did it live through twice?
4 July, US Independence Day
Samoa repeated 4 July, US Independence Day, in 1892, living Monday 4 July twice after American traders persuaded King Malietoa Laupepa to adopt the American date.
Q 23What is a hurricane called once it crosses west of the date line, north of the equator?
France abstained after arguing that the prime meridian should be neutral, cutting through no great continent, neither Europe nor America.
Q 14Which observatory's meridian did the 1884 International Meridian Conference adopt as longitude 0°?
Greenwich
Greenwich was chosen because nearly two-thirds of the world's ships already used charts based on its meridian, so it caused the least disruption.
Q 15Which two major cities are the first to reach each new calendar day?
Auckland and Wellington
Auckland and Wellington keep New Zealand time, so Auckland's Sky Tower fireworks greet the New Year only about an hour after the first small island nations do.
Q 16What new name was uninhabited Caroline Island given in 1997?
Millennium Island
Millennium Island welcomed 2000 with chanting and dance by singers and dancers who travelled out to the normally empty atoll for the occasion.
Q 17Why do three calendar dates briefly coexist on Earth each day?
Zones span 26 hours
Zones span 26 hours rather than 24, so each day the newest date has already begun at one end of the map before the oldest has run out at the other.
Q 18When Russia handed Alaska to the United States in 1867, which calendar did Alaska stop using?
The Julian calendar
The Julian calendar ran 12 days behind the Gregorian one, and Alaska also moved to the American side of the date line, so the 18 October handover was still early October by Russian dates.
Q 19Where did Magellan's surviving crew, sailing home in 1522, first learn from Portuguese islanders that their log was a day behind?
Cape Verde
Cape Verde: the crew had logged every day without a gap, yet islanders said Thursday when the ship said Wednesday; Gasparo Contarini explained that sailing west had cost a day.
Q 20Which Asian country sat on the American side of the date line until the end of 1844?
Philippines
The Philippines traded with Spanish Mexico, so it kept the American date until its trade turned toward China and the Dutch East Indies.
A typhoon
A typhoon: Hurricane John crossed the date line in late August 1994 and became Typhoon John, then crossed back on 8 September and was a hurricane once more.
Q 24Why did Samoa move across the date line in 2011?
To ease trade with Australia and NZ
To ease trade with Australia and NZ: the jump put Samoa three hours ahead of Sydney instead of 21 hours behind it.
Q 25Which neighbour crossed the date line along with Samoa at the end of 2011?
Tokelau
Tokelau's main transport and communications links run through Samoa, so the three atolls followed it across the line, while American Samoa stayed on the American side.
Q 26Which atoll with a US Army missile range skipped Saturday 21 August 1993 to share the Marshall Islands' date?
Kwajalein
Kwajalein moved its workweek to Tuesday through Saturday, so its working days still lined up with Monday to Friday in the United States.
Q 27Why did a republic push the date line around its eastern islands?
The country straddled it, leaving four shared weekdays
The country straddled it, leaving four shared weekdays, so its eastern islands skipped Saturday 31 December 1994 and the line in effect moved east around the whole country.
Q 28As Japan attacked Pearl Harbor in 1941, what was the date in Tokyo?
8 December
8 December, because Tokyo lies across the date line from Hawaii, where it was still the 7th; Japan's landing in Malaya began before the raid yet carries the later date too.
Q 29Which two places sit east of the date line, a whole day behind nearby Samoa?
The Cook Islands and Niue
The Cook Islands and Niue keep the American date, and the Cook Islands got there in 1899 by law: Christmas Day was stretched over two days, so islanders celebrated it twice.
Q 30The meridian the date line mostly follows crosses land in which island nation?
Fiji
Fiji: the meridian cuts right across its island of Taveuni, but the date line bends around the country, so all of Fiji keeps a single date.