• A. Russia
  • B. Indonesia
  • C. Canada
  • D. Australia

💡 Need a hint?

Think of a country with countless islands, bays, and fjords in the far north. What matters is the jaggedness of the coastline, not the largest land area.

✅ View the answer

The correct answer is C. Canada.

A classic surprise. Many people guess Indonesia because of its thousands of islands, or Russia simply because it’s so large, but Canada wins. The explanation lies in the enormous number of islands in the north of the country and the extremely irregular coastline along the Arctic waters, the Atlantic Ocean, and the Pacific Ocean.

Incidentally, the exact length of a coastline always depends on the measurement method. The smaller the unit of measurement, the more detail you capture and the longer the result. This is known as the coastline paradox. But regardless of which method you use, Canada consistently comes out on top.

📚 More background information

The coastline paradox is actually a rather strange idea when you stop to think about it. Imagine measuring the coast of Canada with a 100-kilometre ruler. You would skip over all the small bays and inlets. If you then measured with a 1-kilometre ruler, you would follow far more detail and the figure would grow substantially. There is therefore no single “true” length for a coastline. Yet the relative ranking of countries barely changes: Canada remains at the top in virtually every measurement.

This is entirely due to the Canadian Arctic Archipelago, a collection of countless large and small islands to the north of the mainland. Every island counts. Add the fjords and inlets along the east coast, and the total adds up to a length that leaves other countries far behind.

Why do people so often guess Indonesia or Russia? Indonesia feels like a logical choice because of its thousands of islands, and that country does indeed rank very high on the list. Russia, meanwhile, is the largest country in the world by land area, so it intuitively draws people in. But land area and coastline length are two different things. A large country with a relatively straight coastline has a surprisingly short coastline, while a country with many scattered islands and winding shores accumulates length at a remarkable rate.

For your next quiz night: when questions come up about the longest coastline, it’s not about the biggest country, but about the country with the most fragmented northern coast. Remember that, and you’ll be in good shape.