Passengers on board Capt. Dave's Dolphin and Whale Safari tour boat were treated to a rare sight this past weekend when around 1,000 common dolphins began to stampede off Dana Point in Southern California.

The unusual event happened on Saturday and then on again on Sunday, from when the video below was filmed.

Dave Anderson, the boat's owner, told The Los Angeles Times that throughout his 10 years in business he's almost never seen a pod of dolphins this large charging through the waters at full speed.

"It's one of the most amazing things I've ever seen, and I've seen a lot of beautiful and interesting things," Anderson said.

It's not clear why this happened, but Anderson guesses that the marine mammals may have been chasing something or were spooked.

"We don't know. I know they're not running away from the boat. It seems like they're responding to something but I just don't know what it is," he told the website.

Watch the incredible phenomenon below: