World geography: Identify the country with the longest coastline on Earth. Consider total national coastline length across oceans and seas. Choose the correct country.

Concept

• Coastline length sums all shorelines along oceans and seas under a country's sovereignty.
• Due to its extensive Arctic, Atlantic, and Pacific coasts with countless bays and islands, Canada has the world's longest coastline.

Elimination
Russia also has long Arctic and Pacific coasts; Indonesia and Australia have large coastlines, but all are shorter than Canada's.

Final Answer
Canada.