Wild orcas gently rub their bellies on smooth stones in shallow waters off Vancouver Island, Canada, in remarkable amateur footage taken by a builder who was working nearby.

From a mere few feet away Chris Wilton filmed a pod of orcas, otherwise known as killer whales, at Bates Beach in Courtenay, British Columbia.

'I was at work putting a new roof on a home when we heard what sounded like orca's coming around the corner,' Chris said. 'We ran out front to see and were quite amazed to see what was happening.

An adult and juvenile orca rub their bellies on smooth stones in shallow water of Vancouver Island

Chris Wilton took the footage of the pod of orcas at Bates Beach in Courtenay in British Columbia

'There were four or five orca's coming in and out of the beach and swimming right up ashore within six feet of us.'

Chris says while the intimate footage posted on the internet goes for four minutes and 20 seconds, the display in fact lasted about an hour.

'It was one of the most amazing things I have ever seen,' he added.

The Orca Network posted his video on its Facebook page with a quote from 'The Marine Detective' blogger Jackie Hildering: 'Absolutely remarkable footage of northern resident orcas with their culturally unique behaviour of rubbing themselves on beaches like this.

Wilton said the display lasted about an hour and that 'It was one of the most amazing things I have ever seen'

'The Marine Detective' blogger Jackie Hildering said the display was unique to the northern resident orcas

'I happen to be with whale researchers Janie Wray and Christie McMillan, and we believe these whales are the A42 matriline. The big male is very distinct. He is A66 born in 1996.'

Less scientific but just as bewildered, the group of men witnessing the display were heard saying 'This is crazy', 'Powerful' and 'Holy moly'.

Another added: 'I think they're trying to splash us.'

The orcas swam away from the shore before coming back to rub their underside on the stones

The northern resident orcas are renowned for their belly rubbing behaviour but scientists aren't certain as to why they do it.