The Mariana Trench: Deepest Scar in the Pacific

The Mariana Trench is a crescent-shaped subduction zone in the western Pacific Ocean, ~200 km (124 mi) east of the Mariana Islands, ~2,550 km (1,580 mi) long, 69 km (43 mi) wide.

Challenger Deep (southern end) = 10,929 m (35,856 ft) below sea level—deepest known point on Earth. If Everest (8,849 m) were placed there, its summit would be 2,080 m underwater.

Geology: Pacific Plate subducts under Philippine Plate. Extreme pressure (1,100 atm), near-freezing, pitch black. Yet life thrives: amphipods, xenophyophores, microbial mats, hadal snailfish (Pseudoliparis swirei at 8,145 m).

Exploration: Trieste (1960, Piccard/Walsh), Kaikō (1995), Nereus (2009), Deepsea Challenger (2012, Cameron), Limiting Factor (2019, Vescovo—multiple dives).

Protection: Marianas Trench Marine National Monument (2009, US) – 246,000 km². UNESCO World Heritage candidate.