A drone operator recorded stunning footage of six grey whales off Newport Beach, California yesterday, during their annual migration down to the warm lagoons in Baja California, Mexico.

Grey whales have the longest migration of any mammal, making a round-trip of close to 20,000km from their feeding grounds in the Arctic to their calving grounds in Baja California.

The grey whale migration can usually be viewed in Southern California from late November into April.

"We had an awesome experience on our whale-watching boats today as six south-bound migrating grey whales appeared about five miles [8km] off the coast of Newport Harbour", naturalist and photographer Kristin Campbell said.

"We noticed some of the whales rolling around, touching bellies and one whale proceeded to breach up to seven times right in front of us!"