Complex sentence: The Tuamotus or the Tuamotu Archipelago (officially "Archipel des Tuamotu") are a chain of atolls in French Polynesia and the largest chain of atolls in the world, spanning an area of the Pacific Ocean roughly the size of Western Europe.
Split into simpler sentences: The Tuamotus or the Tuamotu Archipelago (officially "Archipel des Tuamotu") are a chain of islands and atolls in French Polynesia. They form the largest chain of atolls in the world, spanning an area of the Pacific Ocean roughly the size of Western Europe.