Millions of anchovies gathered along shores of Southern California. Scientists there say they haven't seen anything like it in 30 years.

To get a closer look several marine biology professors and their grad students from the Scripps Institution of Oceanography at the University of California, San Diego, took a dip and caught up with the massive school of fish.

One of the students brought a GoPro camera with him, capturing the giant mass of bait fish on film, as well as a curious -- and likely hungry -- leopard shark.

"It was remarkable. From a distance it looked like an oil slick and you think 'What happened?' and then you get up close and it's amazing," said Robert Monroe. "It's like watching the motion of a lava lamp."

"Schools like this exist throughout the region, but I don't know why they butted up right against the surf," said David Checkley, a fish expert at Scripps. "A school this size and this immensity, it's rather difficult to know why."

The school measured some 50 feet in width and stretched 325 feet in length. Scientists estimated it contained anywhere from 1 million to 100 million fish.

As Checkley said: "It's just fish, fish, fish!"