That the deep sea is a place of profound surprises and far more secrets is now likely common knowledge. However, what scientists have recently discovered using the Chinese submersible "Fendouzhe" at depths of up to 9,532 metres exceeds the greatest expectations.
At a depth of 9,500 metres, there is an unimaginable pressure of 950 bar, perpetual darkness, and freezing water temperatures of 2 °C. Compounded by active plate tectonics causing earthquakes and volcanic eruptions along the Pacific Ring of Fire, it is precisely here that life is teeming. Researchers conducted dives along trench faults from the Kamchatka Peninsula to the Aleutian Islands and discovered a 2,500 (!) kilometre-long ecosystem.
The Kuril-Kamchatka Trench and the Aleutian Trench, alongside the Mariana Trench east of the Philippines, are among the deepest trenches in the ocean. All biological communities at these depths share a common characteristic: they subsist on organic matter that descends from above as "marine snow", supplemented by organisms transported down the steep slopes into the trenches. These trenches act as catchments for the upper marine zones. Benthic microorganisms decompose this material, producing methane. This methane, in turn, forms the metabolic basis for other microbes that convert this energy-rich compound into biomass via chemosynthesis. They constitute the primary trophic level for bivalves, tube worms, polychaetes, and smaller vertebrates—a vast biological community documented at depths ranging from 5,743 to 9,532 metres.
The Pacific Ring of Fire extends over 40,000 km along the west coast of South, Central, and North America to the Aleutian Trench, and onwards via Kamchatka, Japan, the Philippines, and Indonesia to New Zealand. What remains to be discovered at depths between 5,700 and 11,000 metres is yet unknown.
These findings support the argument for establishing comprehensive marine protected areas in the deep sea. This environment presents ongoing opportunities for scientific research, alongside the imperative to protect a largely unexplored habitat.
The research paper: https://www.nature.com/articles/s41586-025-09317-z
