On a remote tropical island in the Indian Ocean lies a geologic enigma. Some 4 million years ago, volcanic eruptions on the seabed piled lava upward almost two miles, until it broke above the waves. Then it kept piling up, to form what is now the craggy, densely vegetated island of Anjouan. Like all islands formed this way (think Hawaii) Anjouan is 100 percent dark volcanic basalt. Except for the part that is not. That part-a mass of pure white quartzite, apparent remains of a river or beach deposit formed on some faraway, long-ago continent-is not supposed to be there.
Around 60 years ago, marine scientists on an armada of ships from 14 countries combined their efforts to explore the largest unknown area of earth, the deep waters and seafloor of the Indian Ocean.
They once inhabited the seafloor and have been steadily buried: Microorganisms in the sub-surface sediments at the bottom of the Arabian Sea reveal details of fluctuations in climate and environmental conditions over the past 52,000 years.
Detailed imaging of the seafloor used to search for Malaysia Airlines flight MH370 is providing unprecedented insights into the geological development of the Indian Ocean.
A small, motorised fishing boat heads out to sea from the port of Sinabang, leaving behind the remote island of Simeulue, off the coast of western Sumatra. Noticeable on the deck is a tangle of plastic tubes, linked up to a roaring, spluttering engine. The on-board fishers are going 'compressor fishing', a practice that involves divers searching the seabed for lucrative octopus, grouper and sea cucumber, all the while relying on air supplied by a single plastic lifeline, snaking precariously up to the surface. The rewards can be great - fishers are able to stay deep underwater for long periods, harvesting catches that would be inaccessible to those using other fishing techniques. However, this method is fraught with dangers, as local Simeulue fisher, Anhar, can testify.