The deepest valley in the world is the Challenger Deep, located in the Mariana Trench in the Pacific Ocean.

Here are some details:

* Depth: Approximately 10,924 meters (35,840 feet) below sea level.

* Location: Western Pacific Ocean, east of the Mariana Islands.

* Type: Oceanic trench

* Formation: Formed by the convergence of two tectonic plates, where one slides under the other.

It's important to note that the precise depth of the Challenger Deep is still being refined, as measurements vary slightly depending on the method used.