A group of amateur divers believe they might have discovered the remains of a sailing ship which sank off the city's southernmost island in 1944 - killing more than 50 people, according to historical records.
The group of 12 discovered a cannon, two anchors and several iron chains during a diving trip near the southern tip of Po Toi Island on March 29.
They suspect the relics belonged to the only recorded shipwreck in that area - a vessel carrying around 500 Hong Kong citizens exiled by Japanese invaders.
Jack Wu Ming-chuen, chairman of the Hong Kong Underwater Archaeological Association - to which the divers belong - said the two anchors, each about two metres long, appeared to be admiralty pattern anchors which were invented in around 1808 and not popularised until 1815.
He said the anchors were found about 50 metres off the coast in 15-metre-deep water.
The cannon - also about two metres long - was discovered around 100 metres off the coast in 11-metre-deep water. Wu said it was common for cargo ships around that time to be armed because pirate activities were rampant.
"When the ship was about to sink, people on board would want to get rid of some weight," Wu said. "I guess they might have thrown the cannon away first."