The main mechanism for wind - driven mixing into the deep ocean (down to around 2000 metres) is via convergence of warm tropical surface water in the subtropical ocean gyres. (skepticalscience.com)
Although kelp forests are unknown in tropical surface waters, a few species of Laminaria have been known to occur exclusively in tropical deep waters. (en.wikipedia.org)
The Atlantic Meridional Overturning Circulation (AMOC)- the transport of warm tropical surface water northward - is indeed propelled by dense water sinking in the North Atlantic and travelling equatorward in the deeper layers, but it also has a wind - driven component to it. (skepticalscience.com)