Conflict photographers grapple with two worlds that are themselves often in conflict - the one where bombs fall and bullets fly, where adrenaline runs high, and the other, back home, which is comparatively secure, and where the big event of the day may involve selecting swatches of fabric for a new sofa.

Life feels more vivid in a conflict zone. It is clear what matters, and who you can count on, for what.

Right up until the late 18th century, when the first weighted lines were used to probe the ocean depths, many people believed the seas were bottomless - the watery equivalent of infinite outer space.

In our quest to define and describe the world, we have crisscrossed the oceans and continents, compiling exhaustive knowledge about its life forms and features, and extended our physical reach through technology, which provides us instantaneous and pervasive access to information about seemingly everything.