Deep-sea trenches are some of the deepest parts of the ocean, formed by the movement of tectonic plates. They occur where one plate is forced under another, creating a steep, narrow depression in the ocean floor. The Mariana Trench, located in the western Pacific Ocean, is the deepest known trench, reaching depths of about 36,000 feet. These trenches are home to unique ecosystems and organisms that have adapted to extreme conditions, such as high pressure and low temperatures. Some species found in these depths include giant squid and deep-sea fish, which have special adaptations to survive in such harsh environments.