The term 'Like the Mariana Trench' refers to something that is very DEEP. The crossword solutions for this term are 'DEEP' (4 letters) and 'DEEPEST' (7 letters). The Mariana Trench is the DEEPEST part of the world's oceans, located in the western Pacific Ocean near the Mariana Islands. It has a maximum depth of 10, 994 meters, making it the DEEPEST known point on Earth. Therefore, the term 'Like the Mariana Trench' is used to describe something that is very DEEP.