There have been a lot of interesting maps of late that map out continents and planets, but today is one for the sea—the bottom of which we know less about than the surface of the Moon.
According to a story covered by the BBC, the US State Department backed an exploration of the Mariana Trench, a subduction zone where one oceanic plate is slipping underneath another. The result is an inward-folding crumple and then a bunch of volcanos—the Mariana Islands. The US wants to know if it can extend its economic zone further, but can only do so if certain geographic conditions are met. Hence, the study.
Challenger Deep is the deepest, lowest point on the planet. Though one can argue that because the Earth is not a perfect sphere, points in the Arctic and Antarctic may yet be deeper/nearer the centre of the Earth. If one were to Mount Everest, the tallest mountain on the planet, inside the Mariana Trench at Challenger Deep, the very tip of the mountain would still not break the surface of the ocean.