A common claim is that a ranked list already names the most isolated cities on Earth. The fact is that isolation is a measure, and the measures disagree. Perth is the usual winner on distance. Adelaide, the next large city, is about 2,100 km away, or about 1,305 miles. Sydney is farther. Perth is closer to Jakarta than to Sydney. The population is on the order of 2 million. On Australia’s own ARIA+ remoteness index, which measures road distance to services, Perth scores 0 out of 15, highly accessible. Distance to another metropolis and distance to a supermarket are not the same thing. A list that calls Perth the most remote and a list that calls it highly accessible can both be right.

Iquitos wins a different contest. It is the largest city with no major road connection. Guinness used a figure near 430,000 in an older entry. A more recent urban-core count is about 378,000. The only road that leaves the city stops at Nauta, about 100 km south. Everything else moves by air or by the Amazon. A state-supported ferry covers 487 km to Santa Rosa and has carried more than 450,000 passengers since 2017. A planned pair of fluvial terminals was put at about $205 million. Pucallpa, a road-connected city, is hundreds of kilometres away by river. Isolation here is the absence of a highway, not the kilometres to the next big place. The city survives because it is the transfer point. Fuel, food, medicine, and people pass the docks and the airstrip.

Nuuk is a third measure. The capital of Greenland has about 19,000 people and no road to any other town on the island. The nearest large city, Reykjavik, is on the order of 1,750 km away. Planes and ships are the road. A travel-blog list that puts Perth, Iquitos, and Nuuk in one ranking has mixed a distance between cities, a missing highway, and a missing road network. Getting there can take days on the river. It takes hours by air. Survival is logistics. It is not a shared place on a chart.

Distance to the next large city is a map measurement. ARIA+ is an Australian index of road distance to urban services, scored 0 to 15. A city can be far from the next metropolis and close to its own hospitals. Iquitos is defined by the absence of a highway that leaves the region. The population figures differ by year and by whether the count is the urban core or a wider area.

Nuuk is defined by the absence of a road to any other settlement in Greenland. A flight time and a river time are not the same isolation. A ranked list that puts all three on one axis has chosen a measure and not said so.

It is settled that Perth is about 2,100 km from Adelaide, that Iquitos has no major road out, and that Nuuk has no road to any other town. It is not settled that one of them is the most isolated. Use 2,100 km for Perth. Use the missing highway for Iquitos. Use the missing road network for Nuuk. Do not put them on one rank.