PLEASANTON — The bodies of a man and his adult son were recovered from a lake Monday morning, less than 15 hours after they went overboard from a large raft.

Divers found the 59-year-old man and his 34-year-old son around 10 a.m. in the same area where they went into the lake at the Shadow Cliffs Regional Recreation Area, spokeswoman Carolyn Jones of the East Bay Regional Park District said. The two were not identified immediately.

The search resumed Monday morning around 8 a.m. The two men were first reported to be in the water around 7 p.m. Sunday, when they were out in a large raft with about seven family members on the 40-foot-deep lake, Jones said.

The part of the lake where the tragedy occurred is designated as one where visitors must swim at their own risk and is not monitored by lifeguards, Jones said. Neither man wore a life jacket, even though they didn’t know how to swim, she said.

People on the raft and in the area tried to rescue the men but were unsuccessful, Jones said.

Dive teams from the East Bay Regional Park police and Alameda County Sheriff’s Office were used.

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.