The idea of going over the side of a cruise ship is horrifying. One minute a person is safely on deck, and the next the passenger has plunged several stories into inky water, often never to be seen again.
It's a story that's been written more frequently now that cruising has become increasingly affordable with ships built to hold a small city's worth of people. But amid a growing chorus of accusations about security leveled at the cruise industry, insiders say passengers and crew need to take more responsibility for their own safety.
"There's been a lot more binge drinking than I've seen in the past," said Douglas Ward, a cruise expert who has reviewed the industry for 43 years.
Ward, who lives in Southampton, England, and has written more than two dozen editions of the "Berlitz Complete Guide to Cruising & Cruise Ships," told ABCNews.com that most people who go overboard do so at night after a bout of heavy drinking.
In the past few weeks, two people have gone overboard on major cruise ships. Jennifer Ellis Seitz, 36, went over the balcony of the Norwegian Pearl cruise ship Christmas night. While her family has said the Florida woman may have jumped, authorities are still investigating.
One week later, on New Year's Day, a man identified as Carnival Sensation employee Antonio Matabang of California went overboard -- fellow crew members who saw him fall off the ship near the coast of Florida reported it. The search for his body has since been suspended.
Because cruise lines do not report crimes and accidents to one central authority, it's difficult to gauge exactly how many people go overboard each year. One informal cruising Web site puts 2008's total at eight, down from 20 in 2007 and 22 in 2006.
"The overboards always seem to me to be from the larger ships," Ward said.
Those would be the "resort ships" that dominate the industry -- those run by mainstream lines such as Holland America, Carnival, Celebrity, Royal Caribbean International and Norwegian Cruise Lines that can carry thousands of passengers and crew at a time.
While cruises used to be only for the elite, larger ships and cheaper tickets have made them the vacation everyone can afford -- older people living on a fixed incomes, families with young children, college students.
"As the age range goes down, it's more a question of drink and showing off," Ward said.
In 2008, about 16.8 million people took cruises, more than 11 million of them Americans, Ward said. That's up from about 9.4 million cruise passengers in 1999 and 500,000 in 1970.
While each overboard incident typically makes numerous headlines, the number of people who actually go over the side of ship is tiny compared with the number of passengers carried safely.
"It's a very, very small percentage," Ward said. "Of course, we don't want any."
While Carnival hasn't released information on Matabang's disappearance other than to say it was searching the waters for an employee, Ward said he was told that Matabang had been standing on the ship's railing for a photograph, "which is absolutely forbidden" and "stupid on a moving ship."
While cruise ship personnel can't watch every guest at every moment, the cruise lines said they have been making security changes to accommodate the growing number of passengers.