Recovery mission to take place for Perth teen swept out to sea at Scarborough Beach

The search for a teenage boy swept out to sea after going swimming at a Perth beach has turned into a recovery mission today.

The 16-year-old was one of a group of four who plunged into the ocean at Scarborough Beach at 8pm on Monday.

A beachgoer heard cries for help and immediately alerted authorities.

Three of the four friends made it back to shore, sparking a frantic search for the teen by the Air and Water Police.

The rescue mission was scaled back yesterday due to high winds and poor water visibility.

"They were close to shore — whether or not it was a rip that took them out, or they were hit by a wave, is unknown to us as this stage," Acting Inspector Cindy Morgan said.

Several beachgoers were quick to take the plunge and help with the rescue.

"I grabbed my surfboard and we went down to the beach and the police were sort of wading in the water, looking for them," witness Jack Taylor told 9News.

While his friends and family watched from the sand in hope.

9News understands the missing 16-year-old boy was living in Perth with relatives.

His mother in Ethiopia has been told her son is missing.

The teen was not an experienced swimmer and locals told 9News ocean rescues were common at the beach.

"I surf here and I swim here, and I save people all the time," witness Violet Kotnowska said.

"This is a really dangerous part of the beach, and people have to realise it is more dangerous than it looks."