The ocean is full of dangerous and amazing things, and this phenomenon is truly a sight to behold.

Just off the coast of Scripps Pier in La Jolla, Calif., unusual underwater activity has scientists scratching their heads. Though the dark splotches could be mistaken for an oil spill, the truth is much more bizarre. As seen in the video below, a massive school of anchovy congregated in the shallow water, gathering with such density that they appeared to create dark bands in the typically clear water.
The footage was taken on July 8, 2014, and an article from the Scripps Institution of Oceanography at the University of California, San Diego claims that this sort of behavior has not been observed in over 30 years. As such, they are still unsure of what caused the anchovy to behave so strangely. Regardless of the reason, however, the sight of all the fish is breathtaking.