Which oceanic trench is about 2,550 km long and 69 km wide?

The oceanic trench about 2,550 kilometres long and 69 kilometres wide is the Mariana Trench.

The Mariana Trench is a crescent-shaped depression in the western Pacific Ocean, roughly 200 kilometres east of the Mariana Islands. Its extreme depth results from subduction: the Pacific Plate bends and sinks beneath the smaller Mariana Plate, creating a deep boundary between the two tectonic plates.

At the trench’s southern end is Challenger Deep, a slot-shaped valley that reaches nearly 11,000 metres below sea level. It is the deepest known point in Earth’s oceans. The trench’s length and width describe the overall geological feature, while Challenger Deep refers only to its deepest section.

The trench is sometimes confused with the Tonga Trench, which is also in the Pacific and among the deepest oceanic trenches. However, the Mariana Trench is the best-known record-holder. Jacques Piccard and Don Walsh first reached Challenger Deep in 1960 aboard the bathyscaphe Trieste; James Cameron made a solo descent in 2012.