Prior to his historic dive to the bottom of the Mariana Trench, James Cameron explored the 8.2 km deep New Britain Trench, a region never before explored by human or robot:
In terms of biology, the New Britain Trench looked like New York City compared to the desert at the bottom of the Mariana Trench. On dives with the submersible and with robotic vehicles, the team found thriving communities of acorn worms and sea anemones at the bottom of the New Britain trench, which were fed by nutrients coming from nearby islands. “There was a lot of nutrient input,” says Douglas Bartlett, a microbiologist at the Scripps Institution of Oceanography in La Jolla, California. “It was incredible to see logs at 8.2 kilometres.”
via Nature, The Scuttlefish.