Several cities claim to be the most isolated, the most remote, the furthest from something. Almost all of them lose the title when you change the criterion slightly.
That is not a criticism. It is what isolation actually is — a measurement, not a fact.
PERTH — the most isolated major city, unless you measure it differently.
The claim was popularised by Bill Bryson and Perth residents will tell it to you within an hour of your arrival. The nearest city of more than 500,000 people is Adelaide, 2,104 km away in a straight line, across the Nullarbor Plain — whose name is Latin for no trees and which contains the longest straight stretch of road in the world. Perth is closer to Jakarta than to Sydney.
Change the criterion to "nearest city of more than a million" and the most remote city on Earth is Auckland, 2,153 km from Sydney.
That is 49 kilometres further. Perth loses its defining characteristic by the length of a commute.
ÜRÜMQI — the furthest city from any sea, depending on where the sea is.
Ürümqi holds a Guinness record as the most remote city from any sea, roughly 2,500 kilometres from the nearest coastline. It is the closest major city to the Eurasian pole of inaccessibility, about 320 km north in the Gurbantünggüt Desert.
The caveat is good. The classic location depends on an older definition of what counts as ocean. Include the Gulf of Ob, an Arctic inlet in northern Russia, and the calculation shifts; researchers publishing in the Scottish Geographical Journal proposed two alternative points. There are now three competing candidates, all in northern Xinjiang.
→ Ürümqi
HONOLULU — the one that wins on the strictest measure.
By the "nearest city over 500,000" criterion, Honolulu beats everyone: about 3,841 km from San Francisco. Hawaii also abandoned daylight saving in the 1960s, because at 21° north the longest day of the year runs about 13 hours 26 minutes and the shortest about 10 hours 50 — not enough seasonal variation to be worth adjusting for.
→ Honolulu
CHATHAM ISLANDS — six hundred people, eight hundred kilometres out.
About 800 km east of New Zealand's South Island, permanent population around 600. They set their clocks 45 minutes ahead of mainland New Zealand informally in 1945, and Parliament legalised it 29 years later.
They also hold about 350 black robins, every one descended from a single female that died in 1983 — the species was down to five birds in 1980.
REYKJAVÍK — a capital with no land neighbours.
At 22° west on UTC+0, running about ninety minutes ahead of its own sun, with around 1,230 hours of sunshine a year — and at least 85 to 90% of its homes heated by water pumped out of the ground.
LHASA — isolation by altitude.
The Potala Palace stands at about 3,700 metres, holding the Guinness record for the highest-altitude palace. Lhasa keeps Beijing Time, calculated for a meridian nearly 4,000 kilometres to its east.
→ Lhasa
So: every one of these places is genuinely remote, and every claim about how remote depends on a definition somebody chose. Change the definition and the ranking moves — which is also, as it happens, exactly how time zones work.