Realising it was a once-in-a-lifetime event, an 18-year-old boy from New South Wales, Australia, captured an underwater footage of a tiger shark tearing into a humpback whale carcass off the south coast.

The teenager, Michael James, braved the jaws of the mighty predator by walking into the ocean at Broulee, which is on the state's south coast, until he was knee-deep in water.

James' footage shows a shark moving in circles around the carcass of a humpback whale. The shark then takes a bite of the carcass that is stuck between rocks on the beach. James was so engrossed in shooting the video that for a moment he lost his footing and slipped on seaweed.

"It took a bit of guts to get in there and have a crack at it. My girlfriend's right into her footage, I thought I'd get this for her and she'll be happy," James told Channel 7's Sunrise.

It was not only James who witnessed the entire episode. There were other residents as well who told Sunrise that it wasn't one shark, but four of them were feeding on the whale carcass. One of the residents, who had come with his daughter, said that he wanted to take a dip into the ocean to witness the event, but his daughter asked him not to do so.

Even though he did not take a dip into the ocean, he witnessed quite a bit. "The shark would come and chomp on the whale, swim away 20 minutes later roughly and come back and chomp on it again go digest it, come back. It was quite amazing," Daily Mail quoted him as saying. 

The beaches at North and South Broulee, Shark Bay, Moruya and North Head were closed for swimmers and other visitors until the sharks had gone away. The shark experts on the beach said that it was not uncommon for sharks to feed off a carcass as the species is known as the "garbage cleaner of the sea".

Watch the video below: