“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.
If you want to follow in the footsteps of the great explorers, forget the moon and Mars: the ocean floor is where the real action is. The deep ocean, the part that’s deeper than 200 metres, covers about 66% of the Earth’s surface. Most of it has never been surveyed in detail. Even less has been seen up close. If the current rate of observation continues, a complete visual survey of the ocean floor will take about 5m years.
While the deep ocean remains out of sight and out of mind, its effects are omnipresent. The deep ocean, with its immense ability to store heat, functions as the planet’s thermostat. The oceans also absorb roughly 30% of the carbon dioxide we pump out into the atmosphere, and generate 80% of our oxygen (though about half of this stays in the ocean itself). As physicist Helen Czerski brilliantly demonstrates in her 2023 book The Blue Machine: How the Ocean Works, the oceans are the motor behind that huge engine of circulating heat and water vapour we call the weather.”
