What is the deepest trench in the Indian Ocean?

The deepest trench in the Indian Ocean is the Java Trench, also known today as the Sunda Trench. Its deepest point reaches roughly 7,290 metres (23,920 feet) below sea level, making it deeper than any other known location in the Indian Ocean.

The trench lies south of Indonesia and extends for about 3,200 kilometres from near the Lesser Sunda Islands past Java and Sumatra toward the Andaman Islands. It formed where the Australian-Capricorn tectonic plates descend beneath the Sunda portion of the Eurasian Plate, a process called subduction.

The name can cause confusion. “Java Trench” remains a familiar and historically established name, while “Sunda Trench” is increasingly used because the feature extends well beyond Java. The trench was also central to research following the 2004 Indian Ocean earthquake and tsunami. In 2019, the Five Deeps Expedition directly measured its deepest area and confirmed that it is deeper than the Dordrecht Deep in the Diamantina Fracture Zone, another contender for the Indian Ocean’s deepest point.