Submarine mountains and waves stir Pacific Ocean depths

Friday 30 January 2026 - 11:50

By: Dakir Madiha

Submarine mountains and waves stir Pacific Ocean depths

A fresh study unveils surprising activity in the deep Pacific Ocean, where waters just above the seafloor churn dynamically under the influence of distant surface waves and underwater topography. Far from the static abyss many imagine, this bottom boundary layer fluctuates dramatically in thickness, shaped by submarine mountains and tidal-generated waves that propagate from thousands of meters above.

Researchers, led by Dr. Jessica Kolbusz from the Minderoo-UWA Deep-Sea Research Centre at the University of Western Australia, merged expedition data from a trans-Pacific voyage with two decades of historical ocean observations. Applying machine learning techniques for the first time to analyze the lower mixing layer, they found its depth varies from under 100 meters in some spots to over 700 meters in others. This critical zone, known as the benthic mixed layer, sits directly atop the ocean floor and drives the exchange of heat, nutrients, and sediments between the seabed and deeper waters. It also initiates water's gradual return to the surface as part of global ocean circulation.

The team's analysis revealed that seafloor depth, internal tidal energy dissipation, and bottom slope are key factors dictating the layer's thickness. Submarine ridges and mounts trap and agitate water, fostering persistent turbulence across vast expanses and long timescales. Low-mode internal waves from remote tides, rather than local high-frequency events, primarily control these patterns, according to the Random Forest model employed in the study published this month in Ocean Science.

These insights carry weight for climate modeling and emerging deep-sea industries. The layer's dynamics affect how oceans store and redistribute heat, potentially refining long-term climate forecasts where many models oversimplify seabed mixing. As interest in seabed mining rises, understanding how disruptions might ripple through this zone grows urgent, especially with the UN High Seas Treaty taking effect on January 17, 2026, to regulate areas beyond national jurisdictions. Nearly half of the Pacific's abyssal plains have warmed steadily over the past three decades, underscoring the need for such remote observations to inform ocean governance. "The deep ocean is not a silent, static place," the researchers noted. "It is active, connected to surface waters, and constantly evolving."