The deep-sea abyss that briefly held the title of the world's deepest point

Countries & Cities · Published 30 September 2026 Swipe more like this →

In short: In 1874, a single oceanographic survey revealed a depth so profound it briefly dethroned the Mariana Trench. Today, the Kuril–Kamchatka Trench remains a massive, volatile scar on the Pacific floor, driving intense volcanism and powerful tectonic shifts.

The Kuril–Kamcha Trench, also known as the Chishima Trench, is a massive submarine depression in the northwest Pacific Ocean. Stretching approximately 1,800 miles (2,900 km) from north to south, it parallels the Kuril Island chain and meets the Japan Trench east of Hokkaido. This geological feature covers a vast area of roughly 102,000 square miles (264,000 square km).

The trench's existence is driven by a subduction zone where the Pacific plate is forced beneath the Okhotsk plate. This process, which began in the late Cretaceous period, created the Kamchatka and Kuril volcanic arcs. The tectonic movement is highly active; the convergence rate varies from approximately 75 mm per year in the north to about 83 mm per year at the southern end. As the convergence becomes more oblique toward the south, the stress is partitioned into both thrust and strike-slip earthquakes, causing the Kurile forearc to translate westward.

The trench's history includes a brief moment of global fame. During an 1874 survey by the USS Tuscarora, researchers detected a depth of 8,513 meters (4,655 fathoms). At that moment, it surpassed the 7,086-meter depth recorded by the Challenger expedition in the Mariana Trench, making it the deepest known point on Earth—until the Mariana Trench reclaimed the record just one year later. While depth estimates vary between peer-reviewed reports of 9,600 meters and other measurements reaching 10,542 meters, the trench's steep slopes are notable for terraces that may be scars from massive, collapsing sheets of rock.

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