Lucas Ransom, 19, was boogie-boarding with a friend on Friday when he disappeared under the water off Surf Beach.
A shark, believed to be a great white, mauled his leg, and he died shortly after.
Ransom, who was from Riverside County, was an avid swimmer and also a lifeguard. He was a junior at the University of California-Santa Barbara where he was majoring in chemical engineering.
Air Force officials increased patrols of base beaches during the three-day closure, but there have been no reports of other shark sightings after the Friday attack.
Two other beaches owned by the base, Minuteman and Wall beaches, remained closed Monday.
The last shark attack at Surf Beach was in 2008 when a shark bit a surfer's board. The surfer was not injured. The last fatal shark attack happened in 2003 at Avila Beach.