Emergency crews were sent to the popular tourist spot Monday night after witnesses reported a woman had fallen over the railing of the fourth-floor deck and a man jumped about 15 feet into the water to rescue her, said fire department spokesman Steve Yamamoto. The 40-year-old man was described as the woman's boyfriend.
The woman was rushed to a hospital in critical condition but later died, said Lt. Cheryl MacWillie with the Los Angeles County Coroner's office. Her name and age were not immediately released.
The death was being investigated as an apparent accident, police said.
The woman had apparently been drinking with her boyfriend and lost her balance, according to MacWillie. The coroner's office will determine the exact cause of death and whether alcohol or other factors played a role in the fall.
Temperatures in Long Beach dipped into the 40s Monday night and water temperatures were in the low 60s. The woman's boyfriend was being treated for hypothermia and was expected to recover.
Two police officers and a ship employee also got in the water in an attempt to save the woman, but they were not hurt, police said.
Ship officials released a statement offering "sincere condolences to the woman's family regarding this very sad tragedy."
Built in Scotland in the 1930s, the Queen Mary made Long Beach its permanent home in 1967. The ship has a hotel offering 314 original staterooms.