According to Baldwin, UFOs have been reported for years off the coast of San Diego. He says the spinning motion of an underwater flying saucer could create the whirlpool effect seen in the footage. Scientists at the Scripps Institution of Oceanography are extremely skeptical of the UFO theory. Bill Schmidt does extensive research on ocean rip currents. He says the spinning motion in the video looks like it's a giant eddy, possibly caused by two competing ocean currents.
Rip currents run perpendicular to the shoreline, flowing straight out to sea.
When they get outside the surf zone they sometimes collide with long-shore currents heading north or south. When the two currents come together a spinning, eddy motion can result. There is also a deep canyon off the coast of Black's Beach, which can make ocean currents unpredictable. But since the video is so short, Schmidt says it's difficult to say exactly what caused the eddy. No one is certain how common these whirlpool currents are off the San Diego coastline.