A man has gone missing in waters off Esperance, with a full-scale search operation under way.

The 21-year-old man was swimming with friends at Twilight Beach about 4.10pm on Thursday when he was swept into the ocean.

Unable to get back to land, the man was thrown a life preserver, but was taken further out to sea by the swell.

Police, SES and volunteer marine rescue and Esperance Surf Life Saving Club responded and started a search shortly after.

The rescue jet was also deployed to search from the air.

The man was not found before last light, but the operation is again under way.

Police urge members of public not to use drones or water vessels in the vicinity of Twilight Beach as they may impede search efforts.