
In Our Time: Science The Mariana Trench
Feb 19, 2026
Alan Jamieson, deep-submergence explorer and hadal ecologist. Jon Copley, ocean exploration and deep-sea biology communicator. Heather Stewart, marine geologist specializing in subduction trenches. They describe descending into the Mariana Trench, engineering challenges of hadal exploration, trench geology and sediment flows, bizarre deep-sea life like snailfish, pervasive human debris, and the science and conservation questions that keep researchers returning.
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Mariana Trench Formation And Visuals
- The Mariana Trench is a 2,550 km long subduction trench formed where the Pacific plate dives under adjoining plates, creating depths to 10,925 metres.
- Heather Stewart described visible seafloor features from hemipelagic clays to exposed mantle and carbonate vent chimneys like Shinkai.
Unplanned Dive Found Sulphur Mounds
- Alan Jamieson described an unplanned dive to Serenity at ~10,700 m where they found big sulphur mounds and surprising geology.
- He emphasised several successful deep dives in a short series when no one expected multiple trips would work.
Engineering Limits Are Pressure And Communication
- Deep submersibles face two core challenges: immense static pressure and long-distance acoustic communication with the surface.
- Alan Jamieson explained pressure is handled by thick titanium spheres while acoustic modems and undersea tracking are the harder problems.











