That History channel documentary was interesting, but also kind of annoying. They showed that 3D zoom into the trench like 20 times throughout the video and they kept saying the exact same info over and over again, as if we have really poor memories and attention spans. Also, there were some informational errors in there. While the Mariana Trench IS the lowest elevation in the Earth's crust and the lowest part of the ocean, it is NOT the closest part of the Earth to the core. It kind of surprised me that the History channel doesn't even know basic geology. The Earth is not a perfect sphere. The closest part of the seafloor to the center of the Earth is around the north pole.