Deep Ocean: Descent into the Mariana Trench: Exploring an unknown world 10,000 m beneath the waves. After capturing a giant squid on film, NHK's deep-sea film crew explores our planet's deepest point The Mariana Trench is nearly 7 miles deep. The water pressure is immense, and it's a world that's long been out of our reach. What creatures could survive such hostile conditions? This is an expedition to explore the earth's deepest frontier. Narrated By David Attenborough.