The Sai Kung shark featured in a video that grabbed attention online last week is believed to be a more dangerous species that originally thought, and one that has never before been reported in Hong Kong waters.
Marine ecologist Dr Andy Cornish believes the shark is a silvertip shark rather than a sandbar shark, as first thought.
"The shark in the video does have a distinct white patch on the tip of both pectoral fins, which is a distinctive feature of a silvertip shark," Cornish said.
"It is potentially more dangerous to humans than the sandbar, but reports of people being attacked by silvertips have generally been when there has been bait in water or they've been spearfishing and they're dragging dead fish behind them.
"I have dived with silvertip sharks and they normally come and take one look at you and just disappear. They're not interested in humans and generally avoid people."
The video shows the 1.8 metre shark emerging from the sea to shock two Cantonese-speaking anglers at the water's edge. The two-minute clip had earned more than 33,700 YouTube views and more than 2,650 Facebook shares as of last night.
A government spokeswoman said it had not received any reports of shark sightings in the Sai Kung area, but had asked lifeguards to be extra vigilant.
The last reported shark attacks in Hong Kong occurred in 1995 when three swimmers were killed within 10 days near the Sai Kung Peninsula.