Twenty-one-year-old Stefan Wagner was swimming in Spooner's Cove near San Luis Obispo Thursday, and when he dove beneath the surface he never came back up.
Search and Rescue teams scoured the area, which is inside the Montana De Oro State Park. But they called off the search at nightfall.
Wagner's father said he is a great swimmer. The Cal Poly student played water polo in high school and often body-surfed. Wagner also used to dive for abalone and lobster.
The area he was last seen is notoriously treacherous. Another Cal Poly student went missing near Spooner's cove back in 2006.