While it is wise to get out of the sea until one knows what kind of shark it is, most people have little knowledge about these marine beasts.
At least a dozen types of sharks have been recorded in Hong Kong waters over the past 150 years. And some of these creatures are now considered extremely rare, verging on extinction, says Tracy Tsang Chui-chi, a senior programme officer on sharks with WWF Hong Kong.
Tsang says summer is a high season for shark sightings because the predators move up the coast as the seas warm, and back down when the waters cool. Sai Kung and Stanley are prime sighting areas.
The most commonly found species are blacktip reef, grey reef and bamboo sharks. But tiger, whitecheek, hardnose, spottail, milk, grey sharpnose and spadenose sharks, as well as hammerheads, also prowl the city's seas.
Sharks have been responsible for 10 fatal attacks across the territory since records have been kept, reports the Shark Attack File website, which monitors such incidents worldwide.
The last and worst assault happened in 1995 when three swimmers died over 10 days. It was suggested that a great white, the world's largest ocean predator, might have been the culprit behind the local attacks, but this was never confirmed. This torpedo-shaped giant with a powerful tail can grow up to eight metres long and weigh up to 3,400kg.
Researchers found the naturally curious hunters are "sample biting" then releasing their victims - rather than preying on humans.
"It does not make a comforting distinction, but it does show that humans are not actually on a shark's menu," Tsang said.
Tiger sharks are second only to great whites in recorded attacks on humans. But with an undiscerning sense of taste - they eat anything from tyres, tins to other sharks - they are less likely to swim away after taking a bite like giant whites do.
Hammerheads are plentiful and known to approach reefs around Port Shelter and the Ninepin Islands. But as fishermen hunt them down for their fins to be served in a traditional soup, they are gradually disappearing from the city's waters.
The brown-coloured blacktip reef shark lives in shallow waters around coral reefs and is thought to have a breeding ground in the waters just north of Chek Lap Kok. It grows up to two metres long, may become aggressive to those spear fishing and has been reported to bite people wading in shallow water.
Yet normally, the risk of a shark attack in our waters is slight and was much reduced when the government installed shark nets to protect swimmers at 32 popular beaches.
Whale sharks are a rare sight in Hong Kong. These gentle giants can grow as long as 12 metres, the width of a bus.
However, Tsang says, unlike aggressive predator species such as tiger and great white sharks, whale sharks pose no threat to humans - they feed on plankton.