The Philippine Deep is in the floor of the Philippine Sea. The German ship Emden first plumbed the trench in 1927. In comparison, the world’s deepest part of the ocean is the Marianas Trench, which is over 11,000 meters below the seal level.
The Philippine Trench is the result of a collision of tectonic plates. The Philippine Sea Plate is subducting under the Philippine Mobile Belt at the rate of about 16 cm per year (from Wikipedia).
Long live Philippine marine life!