Deep sea trenches are found primarily in the Pacific Ocean, specifically along the western margin where the Pacific Plate subducts beneath other tectonic plates. This is why the Pacific Ocean is also known as the "Ring of Fire" due to its high concentration of volcanoes and earthquakes.

Here are some examples of where deep sea trenches are found:

* Mariana Trench (the deepest point on Earth)

* Peru-Chile Trench

* Japan Trench

* Kuril-Kamchatka Trench

* Tonga Trench

While the majority of trenches are found in the Pacific, some also exist in other oceans:

* Puerto Rico Trench (Atlantic Ocean)

* South Sandwich Trench (Atlantic Ocean)

* Kermadec Trench (Southwest Pacific Ocean)

These trenches are formed at convergent plate boundaries where two tectonic plates collide. The denser plate subducts (sinks) beneath the less dense plate, creating a deep depression in the ocean floor.