A 37-year-old man realised the strength of waves on Sunday afternoon when he was rescued by Tenby's inshore lifeboat and other swimmers from South Beach, Tenby.
The man from Pontypool had been wading chest deep in the sea when a large wave knocked him off balance.
The undertow quickly took his legs and he was unable to get back into shallower water.
Members of the public waded in to assist him, but most were unable to reach the man.
Fortunately, one person managed to reach him and held his head above water until the inshore lifeboat arrived.
The man was taken aboard the lifeboat and returned to the safety of the beach where he was attended to by Tenby coastguard team and an after his misadventure.