natural oil slick on surface 2013 01-04 SB Channel-a-003
When two ocean currents come together a glassy "slick" is formed on the surface.  Oceanographers call this an oceanic front.
Natural Seepage:  Oil and tar slick line.
Two Common Dolphins swim underneath a heavy oil slick in the Santa Barbara Channel.
A Black-Footed Albatross (Phoebastria nigripes) samples the slick line.
natural oil slick on surface 2013 01-04 SB Channel-a-003
natural oil slick on surface 2013 01-04 SB Channel-a-003
natural oil slick on surface 2013 01-04 SB Channel-a-003
See photo in original gallery.