A skipper of a pleasure craft travelling back from Rottnest alerted Police around 8:10pm that three people had fallen overboard.
Two women and a man were at the rear of the boat when they fell overboard due to unknown causes, approximately 4 nautical miles west of Swanbourne.
Water Police immediately began search activities, using police airwing, boats, and assistance of various craft from Fremantle.
The vessel was located quickly and assisted back to Fremantle with the skipper on board.
After a 2 ½ hour search the three missing people were located in the water and taken to hospital where they are being treated for exhaustion.