Police divers are currently searching for a man who was last seen at a popular swimming spot near Collie.
The man in his 20s went swimming in Stockton Lake around 3.15pm on Sunday.
Police say the man required assistance but members of the public who were on the shore were unable to help him.
The search is continuing today, while the lake has been closed off to the public.
Stockton Lake is a popular camping spot and was once a mine site before it was filled with water to form an artificial lake.
Construction contract awarded for Kwinana Freeway upgrade
Port Kennedy humpback whale buried at landfill facility
Secret Harbour by-election: Where to vote on August 29
Mandurah man charged over role in alleged sophisticated cybercrime syndicate
Locals urged to look out for man who removed electronic monitoring device
Four charged over brutal Warnbro home invasion allegedly linked to illicit tobacco trade
UPDATE: Sadly the whale has died overnight
City of Rockingham records steep increase in animal cruelty complaints related to untreated medical conditions
Accused dirt bike hoons charged by Mandurah Police