Emergency crews were sent to Point Lobos State Natural Reserve around 2:45 p.m. Friday where they found lifeguards performing CPR on one of the divers, said state Department of Forestry and Fire Protection spokesman Daniel Berlant.
Lifeguards and firefighters used a boat to get to second diver floating just offshore.
"At that point, we got in a boat with State Parks lifeguards and located the second victim floating in the water about 50 feet from the rocks," Capt. Carlos Aguilera of the Carmel Highlands Fire Department told The Monterey County Herald.
CPR was also performed on that person, but both divers were pronounced dead after being taken to a hospital, officials said.
The names, additional details about the victims and what killed them have not been released, but authorities said one was a male and one was a female.
The reserve where the divers died is a popular diving area about four miles south of Carmel, or about 90 miles south of San Francisco.
The offshore area forms one of the richest underwater habitats in the world, with wildlife that includes seals, sea lions, sea otters and migrating gray whales, according to the state Parks and Recreation Department website, the agency that operates the reserve.
Proof of certification is required, and diving is permitted only at two coves within the park, including Whalers Cove, the area where the two stricken divers were found, the website said.
Parks officials did not immediately return calls to The Associated Press seeking details of the incident.