Upwelling bring aquatic life to the surface.

I frequently ride the ferry from Port Townsend to Keystone (Coupeville). Just NW of the Keystone ferry harbor, during strongly outflowing tides, there is a dramatic upwelling of current, apparantly created by large differences in sea floor topography. At the surface, this creates a "boil", and not infrequently, porpoises and sels or sea lions may be seen here, apparently enjoying things brought to the surface by the. Urrent.

Are there other, similar phenomena in the Sound? Are they predictable enough to include in DeepZoom? Is there a simple way to represent them on a chart, and reflect the likely waxing and waning of the current?