The 26-year-old woman reportedly plunged off an upper walkway of the Long Beach ship-cum-hotel, landing in the frigid water below.
According to officials, the woman was drinking with her boyfriend when she lost her balance.
Long Beach Fire Department spokesman Steve Yamamoto said firefighters received a call at about 8:35 p.m. Monday that a woman fell off the ship and a 40-year-old man jumped into the water to rescue her.
Two Long Beach Police officers then jumped into the water to bring both the man and woman out. The officers did not suffer any injuries.
The man, who jumped 15 feet off a lower walkway, is being treated for hypothermia.
The woman was transported to a nearby hospital but later died as a result of her injuries, according to the Los Angeles County Coroner's office.
The Queen Mary is a cruise ship turned haunted hotel and museum that offers visitors a chance to step back in time aboard one of the most famous ocean liners in history. The ship epitomizes the early elegance of the cruise liner - a time when steamships were the quickest and most fashionable way to travel.
She took her maiden voyage in 1936 and was considered the grandest ship ever built at the time. The Queen Mary carried stars like Fred Astaire and royalty like the Duke and Duchess of Windsor. Moonlighting as a war ship during World War II, the cruise liner returned to its original purpose until retiring in 1966.
Since docking in Long Beach, California, several mysterious events have occurred and many consider the Queen Mary to be one of the most haunted places in America with at least 49 reported deaths onboard.