On 8 March 2014, at 1.20am, Malaysian Airlines flight 370 veered off its scheduled route from Kuala Lumpur to Beijing. An hour later, military radar spotted the plane heading west over the Andaman Sea. Six or seven hours later, it is presumed to have crashed somewhere over the southern Indian Ocean, one of the least studied bodies of water in the world.
Just how little we knew about this part of the ocean became clear during the subsequent search for the missing aircraft. Before a proper underwater search could even begin, a vast stretch of seafloor had to be mapped. Over the next three years, a team of ships from Australia, China and Malaysia scanned the bottom with a combination of submersible robots and ship-borne sonar. Together, they charted a swath of ocean roughly 1,500 miles long and 150 miles wide, encompassing an area the size of France. The maps produced from these scans revealed a lost world, full of undersea canyons, crevasses, volcanic plateaux and a single, enormous cliff taller than the Swiss Alps. Even the abyssal plains, thought to be some of the flattest areas on the planet, were home to previously uncharted hills.
