The Mariana Trench is the deepest part of the world's oceans, located in the western Pacific Ocean. It's a crescent-shaped depression in the seafloor, reaching a maximum known depth of 10,984 meters (36,037 feet) at its deepest point, Challenger Deep. This makes it deeper than Mount Everest is tall. 

Here's a more detailed breakdown:

Location:

The Mariana Trench is situated east of the Mariana Islands in the western Pacific Ocean. 

Shape and Size:

It's a long, narrow trench, approximately 2,550 kilometers (1,580 miles) long and 69 kilometers (43 miles) wide. 

Depth:

The deepest point, Challenger Deep, is about 10,984 meters (36,037 feet) deep. 

Geological Context:

The trench is a result of plate tectonics, specifically the subduction of the Pacific Plate under the Mariana Plate. 

Unique Environment:

The Mariana Trench is a unique environment with extreme pressure, low temperatures, and complete darkness. Despite these harsh conditions, some organisms have adapted to life in the trench, including deep-sea crustaceans like Hirondellea gigas. 

Exploration:

It has been explored by various expeditions, including the historic Trieste dive in 1960 and James Cameron's solo dive in 2012.