Complex sentence: On 1 April 2010, the British government Cabinet established the Chagos Archipelago as the world's largest marine reserve, at 640,000 km 2, it is larger than the country of France or the state of California.
Split into simpler sentences: On 1 April 2010, the British government Cabinet established the Chagos Archipelago as the world's largest marine reserve. At 640,000 km 2, it is larger than the country of France or the state of California.