Final answer:
An ocean trench is typically found at a subduction zone, which is a deep and narrow depression on the sea floor where an oceanic plate is forced below another plate.
Step-by-step explanation:
At a subduction zone, you will typically find an ocean trench, which is a topographic depression of the sea floor. This trench is often narrow but very long, and it marks the location where one tectonic plate is being forced beneath another plate and into the mantle. As a result of this plate interaction, we can find some of the deepest parts of the ocean in these trenches, such as the Mariana Trench in the Pacific Ocean.
Subduction zones are essential for the cycle of plate tectonics where old crust is destroyed and recycled into the mantle. An example of an ocean trench associated with a subduction zone is the deep Japan trench along the coast of Asia.