An oceanic trench is a deep, narrow depression in the ocean floor, formed by the subduction of one tectonic plate beneath another. These trenches are some of the deepest parts of the Earth's oceans, with the Mariana Trench being the most famous, reaching depths of about 36,000 feet. Oceanic trenches play a crucial role in the Earth's geology, as they are sites of intense geological activity, including earthquakes and volcanic eruptions. They also serve as unique habitats for various marine life, some of which are specially adapted to survive in extreme conditions, such as high pressure and low temperatures.