The Mariana Trench, sometimes referred to as the Marianas Trench, is the deepest known part of the world’s oceans and one of the most extreme environments on Earth. It lies in the western Pacific Ocean, approximately 200 kilometers (124 miles) east of the Mariana Islands, forming a dramatic boundary between tectonic plates that continues to shape the planet’s geology (National Geographic).

This immense trench is crescent-shaped, stretching roughly 2,550 kilometers (1,580 miles) long and about 69 kilometers (43 miles) wide. Its most famous point, known as the Challenger Deep, sits at the southern end of a narrow, slot-like valley on the trench floor. The deepest confirmed measurement reaches 10,984 meters (36,037 feet), with a margin of error of about 25 meters, making it the deepest directly measured location on Earth (NOAA). Some earlier, unrepeated sonar readings suggest it may be slightly deeper, potentially reaching 11,034 meters (36,201 feet).

To put that depth into perspective, if Mount Everest, the tallest mountain on Earth at 8,848 meters (29,031 feet), were placed inside the Mariana Trench, its summit would still be more than two kilometers (1.2 miles) underwater. This comparison highlights just how extreme and alien this environment truly is.

At the bottom of the trench, conditions are unlike anywhere humans normally experience. The water pressure reaches approximately 1,086 bars (15,750 psi), which is over 1,000 times the atmospheric pressure at sea level. Under this immense pressure, seawater becomes nearly 5% denser, and temperatures remain just above freezing, typically between 1 and 4 degrees Celsius (34–39°F) (Encyclopaedia Britannica).

Despite these hostile conditions, life still exists. Scientists from the Scripps Institution of Oceanography have discovered single-celled organisms known as monothalamea at depths exceeding 10.6 kilometers (6.6 miles). Additional research has shown that microbial life thrives in the trench, feeding on chemical energy rather than sunlight, challenging long-held assumptions about the limits of life on Earth (Science Magazine).

Recognizing its scientific and ecological importance, the United States designated the Mariana Trench as a National Monument in 2009, offering protections to one of the least explored regions on the planet (U.S. Department of the Interior). Even today, fewer humans have visited the Challenger Deep than have walked on the Moon.

The Mariana Trench remains a powerful reminder of how much of our planet is still unexplored—and how resilient life can be in even the most extreme conditions imaginable.