Chris and Monique Fallows have witnessed many extraordinary events while diving off South Africa.

But during two recent expeditions they captured wildly spectacular scenes that may never have been photographed: that of a voracious cape fur seal boldly snacking on large sharks; and dozens of blue sharks gathered around and gorging on an enormous ball of bait fish.

Of the former event, revealing the raw dynamics of the food chain, Chris Fallows said: "There were eight guests aboard our vessel, many of them seasoned wildlife enthusiasts. None had ever seen anything like this as sharks of this size are certainly not usually considered food for seals.

"In more than 2,000 expeditions working with sharks over the last 21 years, this is the only time I have ever seen a seal kill several sharks and I can find no record of such an event happening elsewhere."

The seal consumed the stomach and livers of the first two sharks, before killing three others.

Chris and Monique Fallows run Apex Shark Expeditions and the Apex Predators Facebook page. They allowed the use of these images, which are protected by copyright laws, for this story only.

The company offers seasonal "Sardine Run" expeditions, which coincide with mass schooling of sardines along the coast.

The sardines, in turn, attract all manner of large predators, including diving sea birds and the occasional shark.

But during one of the recent expeditions the crew found an enormous bait ball, in this case anchovies, 25 miles offshore, in blue shark domain. After plunging alongside the bait ball the divers noted the eeriness stemming from the fact that there were few other predators besides about 40 sharks, herding the bait fish like dogs herd sheep, occasionally going in and snapping up mouthfuls.

"This was a first for us and as far as I can research the first time such an event has been witnessed underwater," Chris Fallows said. "Even though our company runs the world famous sardine run expeditions each year, this spectacle was incredible as it was out in the open ocean, 40 kilometers out to sea, in blue water.

"I would be on one side of the ball and suddenly a shark would come through the ball and on occasion bump straight into me. Whilst this was going on tuna were rocketing up all over to grab any anchovies that tried to flee from the sharks. For three hours we drifted with this feeding orgy, with these magnificent bright blue sharks just doing their business. We were simply just observing nature in action, it was insane."

The Fallows' next scheduled sardine run is in June.