Waters off Sai Sha Road in Sai Kung. Photos: Google Maps, Hong Kong Underwater Association

A 36-year-old Russian woman drowned while finswimming in Sai Kung in the New Territories on Friday.

At 11am, the woman and her 66-year-old boyfriend, of Portuguese origin, were swimming in the sea off Nga Yiu Tau Tsuen on Sai Sha Road in Sai Kung, where they lived, Oriental Daily reported. The man went back home first and left the woman, who was swimming with a monofin, alone.

After an hour, when the man looked out from his balcony, he saw his girlfriend floating in the water. He called police immediately.

The woman was unconscious when firemen arrived. She was sent to hospital but was certified dead later.

Villagers living nearby told the police that the woman had suffered  cramps at least twice while swimming, Sing Tao Daily reported.

Police said initial investigation showed no signs of foul play.

Finswimming is a sport in which the swimmer uses either a monofin or two fins, either on the surface or underwater. For underwater swimming using this method, breathing equipment is needed.