The 25 Largest Islands in the World in 20251. Greenland – The Largest Island on EarthCovering approximately 836,330 square miles, Greenland takes the top spot as the largest island worldwide. Located in the Canadian Arctic Archipelago, it features stunning fjords, glaciers, and Arctic wildlife, including polar bears and Arctic foxes. Great Britain – The Largest UK IslandSpanning around 88,000 square miles, Great Britain is the largest island in the United Kingdom. In 2025, these islands continue to fascinate with their unique landscapes, ecosystems, and cultural histories.