"Shark attack kills diver off Mendocino coast
His companion says fish struck suddenly
Cliff Zimmerman was only three feet away from Randy Fry, his old friend and diving partner, when he heard a noise and felt the pressure of something big moving by.
It was a shark, and it came out of nowhere, it came fast, and it killed his partner.
"I heard a noise, like 'whoosh,' like a submarine, like a boat going by fast. It was a shark,'' Zimmerman said. "I knew it was a shark. It almost brushed me. I saw its dorsal fin. I don't know what kind it was; all I know is, it was big. Big. It was big enough to kill.'' "
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/08/17/SHARK.TMP
"Unprovoked White Shark Attacks on Divers
During the Twentieth Century divers constituted the largest number of victims for any of the four victim groups: divers, surfers, swimmers, and kayakers. There were 108 authenticated unprovoked shark attacks reported from the Pacific Coast of North America, with 50 (46%) directed at divers. The White Shark was determined to be the species responsible in 45 (90%) of the 50 recorded attacks on divers."
http://www.sharkresearchcommittee.com/unprovoked_diver.htm