A body washed up on the beach south of Coral Bay in Western Australia is believed to be that of missing man Robert Shugg.

The 48-year-old has been missing since May 15 when the body of his 41-year-old partner Kathreen Ricketson washed up on the same shoreline at Elle's Beach.

They had been snorkelling at the idyllic holiday spot when something went terribly wrong.

Their two children, a 13-year-old girl and a 10-year-old boy, watched the tragedy unfold from the beach.

A member of the public found the as-yet-unidentified body around midday on Friday.

Police said it would take several days to identify the body.