Tom Caska's drone captured an image of a large shark in the water near surfers. (Aerolens)

KILLCARE, Australia, Sept. 22 (UPI) -- It's a sight no surfer wants to see: A huge shark, circling in the water under his board.

That's exactly the scene drone photographer Tom Caska captured Friday off the New South Wales Central Coast in Australia.


Caska's brother Andrew and a friend were paddling about 50 meters off the shore at Killcare beach, entirely unaware of the massive animal in the water underneath them.

"Andie had a heart attack when he saw this... Scary stuff," Caska wrote on his Facebook, of the moment he and his brother saw the footage.

Based on the size of the surfboards in the image, the shark is estimated to be about 13 feet long and likely a great white. The shark appears to be trailing the large school of fish visible in the water closer to the board, and likely had little interest in the humans nearby.

"Came in after that big school of fish," he wrote. "Must be careful in the water this time of year as the whites migrate sour again."

Great whites are commonly seen in the area this time of year. And last month, 50-year-old Paul Wilcox was swimming about 15 meters off shore when he was bitten in the leg by a great white.