  Marine life has been detected in the ocean's trenches at great depths down to
nearly 11 km. Such life is subject to particular environmental conditions of
large static pressure exceeding 1000 atmosphere. While current flows are
expected to be slow, waters cannot be stagnant with limited exchange of fresh
nutrients needed to support life. For sufficient nutrient supply, the physics
process of turbulent exchange is required. However, the environmental
conditions hamper research in such waters. To study potential turbulent water
motions, a string equipped with specially designed high-resolution temperature
sensors was moored near the deepest point on Earth in the Challenger Deep,
Mariana Trench for nearly three years. A preliminary analysis of a six-day
period when the mooring was still demonstrates hundreds of meters slanted
convection due to internal waves breaking from above. The associated turbulence
dissipation rate with peak values hundred times above the background value is
considered sufficient to maintain deep-trench life. Turbulence associates with
one-ten thousandth of a degree temperature anomalies of about one hour
duration.

Atmospheric and Oceanic Physics