Deep coherent vortices, also known as deep eddies, are deep-reaching mesoscale features that extend from ocean surface to the abyss. These features have been observed within strong meandering current systems in the western boundaries and the Southern Ocean - such as the Gulf Stream, Kuroshio Extension, Brazil-Falkland Confluence Zone, Agulhas Retroflection Zone, and the Antarctic Circumpolar Current around the Drake Passage. Associated with these deep coherent vortices are strong episodic bottom current events on timescales of 1-3 weeks known as 'benthic storms', with near-bottom speeds > 0.2 m/s leading to the resuspension and transport of sediments from the seabed to form the particle-rich benthic nepheloid layers. Despite their seemingly widespread nature, their roles in deep ocean circulation and transport of biogeochemical tracers remain unknown. 

Here we present a compilation of several recent studies with idealised and regional modelling approaches to further understand the formation mechanism of deep coherent vortices arising from surface current instabilities, the mechanism for vertical redistribution of eddy kinetic energy, and their interactions with bathymetric reliefs such as seamounts. We find that the rapid vertical motion of sea surface, combined with the divergence of vertical eddy energy fluxes, plays an important role in the intensification of strong vorticity over the water column. The intensification of near-bottom currents create strong shears and enhance turbulent flows to create a notable bottom mixed layer between 50-100 m thick in idealised simulations. Strong vertical motions capable of transporting fine particles upward arise from ageostrophy due to the curvature of the vortices. Thier interactions with seamounts in the western North Atlantic also lead to enhanced dissipation. The presence of these features raises important questions about their roles for ocean dynamics, deep seabed environment, abyssal biogeochemistry, and implication for processes relevant to climate timescales. 

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