It's the early hours of the morning, and the cruise ship 'Disney Wonder' is ploughing through the Pacific off the west coast of Mexico. In the crew quarters - a surveillance camera captures 23-year-old Rebecca Coriam talking on a phone. Seconds after ending the call, she walks off, never to be seen again.
ANN CORIAM, REBECCA’S MOTHER: We thought, "They must have it wrong or something." Something wasn't right. They just said that she was missing at sea.
Whatever happened to Rebecca on the 'Disney Wonder' remains a mystery. Whether she slipped and fell, jumped, or was pushed into the ocean wasn't properly investigated, and the truth may never be known. Rebecca's is just one of almost 200 cases of people who've vanished at sea in the past decade, leaving behind unanswered questions and grieving families.
JIM WALKER, MARITIME LAWYER: Probably 50% of the disappearances have some factor of foul play.
Maritime lawyer Jim Walker has made a career out of exposing the cruiseline's darkest secrets.
JIM WALKER: The place to get away with a crime is on a cruise ship. The place to be a sexual predator and prey on children is on a cruise ship. If you're a rapist, you're more likely to get away with it committing the crime on a cruise ship on the high seas. All of this is happening out in international waters, typically. There are no policemen on the scene. You can't call 911. You can't summons a police officer who will run onto the crime scene. So they're out there by themselves.
Known as the gateway to the Caribbean, the Bahamas' capital, Nassau, is one of the busiest cruise-ship hubs in the world. Its harbour brims with luxury liners. Last year, it attracted 20 million passengers, turning over a record US$30 billion. But beyond these glittering facades lies a murky world - Where criminals lurk, and crime is rarely punished.
JIM WALKER: It's a cruise industry that new knew, over a decade ago, they had a problem. They tried to solve the problem through slick advertising and marketing, rather than taking the hard steps they needed to really clean their act up.
The glitzy ad campaigns portray a utopian world of wholesome family fun. But accountable to no-one, and with their activities shrouded by centuries-old maritime laws, cruise lines have been concealing the truth about what's really happening onboard their ships.
That veil of secrecy was recently lifted, when a US judge forced one of the industry's biggest operators to hand over its crime figures.
JIM WALKER: Once we had that database, we realised, "My God! None not only do you have crime, you have more crime than a comparable city ashore."
Across the Atlantic, the English city of Chester, with its Roman and medieval walls, seems an unlikely focal point for a campaign to clean up the cruise industry.
ANN CORIAM: Yeah, this photograph of Rebecca when we dropped her off at Manchester Airport, going off on her travels. That it was the first time, wasn't it? Yeah. That's really sad to look at now.
Until early last year, Mike and Ann Coriam had little understanding of the vagaries of cruise-ship crime. With their daughter Rebecca working her dream job looking after children on a Disney cruise ship, they thought they had little cause for concern.
MIKE CORIAM: We got the phone call about 10:45 in the evening, just before we'd gone to bed, from Disney, to say that Rebecca was missing at sea. Then they...
ANN CORIAM: Don't think it gets any easier. I think the longer it goes on, the harder it seems to get.
Reported missing after failing to turn up for work, Rebecca was presumed lost at sea.
ANN CORIAM: They didn't say that anyone had seen her go overboard. They were just saying that she was missing. So we just wanted to get over there, really, as fast as we could.
As the 'Disney Wonder' continued its voyage back to Los Angeles, the Coriams also travelled there to be on-hand when it pulled into port. Expecting that the FBI would be tasked with investigating their daughter's disappearance, they were shocked to learn that there would be no USinvolvement.
MIKE CORIAM: We automatically assumed, as well, that the authorities would get onboard the ship when it docked. But they didn't. It's not national jurisdiction. That's when we started thinking, "Something's not right here." Then we started realising it comes under flags of convenience and where the ship is registered.
The Coriams went aboard, where they were shown the security-camera footage of Rebecca on the morning she vanished.
ANN CORIAM: Well, I asked the captain, "What do you think may have happened to Rebecca?" His words were that she'd obviously made this phone call and walked, then, onto the deck - deck five - probably tried to gather her thoughts, and sat along the side, and a wave could have come and rocked the ship and taken them over.
REPORTER: And you went to that deck?
ANN CORIAM: They took us to the deck.
REPORTER: What did you make of the possibility of it being dangerous, that there could have been some sort of accident?
ANN CORIAM: We didn't think that was possible. I had to get underneath at least a 4-foot veil where there was a huge metal ledge. I couldn't see over it. It was really quite high. I couldn't see how anyone could have gone over, or if they wanted to take their own life, even, would have gone over from that particular part of the ship.
Although no-one had actually seen Rebecca on deck five, the Coriams were pressured into accepting that it was from here that she left the ship.
ANN CORIAM: They brought us flowers to lay there, which we couldn't understand. It was almost like a wake. Everything was laid out for us, really. The flowers were there. We sort of were left there, really. We just couldn't understand it, could we?
JIM WALKER: The Disney people want everyone to believe that a youth counselling can disappear. They want you to believe, "That was just the location of the ship that didn't have a closed-circuit television camera." It's preposterous.
With the FBI refusing to get involved, the investigation was left to a solitary detective from theBahamas, where the ship is registered. He spent just a few hours onboard, interviewing just a handful of crew members before flying home.
JIM WALKER: You had a potential crime scene, put you certainly had evidence that needed to be preserved. You needed a forensic workup off the ship. And you had this one policeman who was out there, literally for just a few hours, on the ship. Then, at the end of the day, the ship turns around and heads back out to sea with another few thousand family members. Imagine - they're bringing their children on this cruise ship where one of the youth counsellors who's responsible for taking care of the children disappeared without a trace.
MIKE CORIAM: This is in the 'LA Times' - in June, they did an article on Rebecca. That was us, watching the ship sail out - Sunday afternoon, Rebecca disappeared.
REPORTER: How did you feel at that time?
MIKE CORIAM: Terrible. Terrible, really. Um... I was thinking on that ship, I was thinking, the week before, she'd have been on that ship.
Contacted by Dateline, as spokesperson for the Disney cruise line said that, while Rebecca's disappearance was heartbreaking for everyone at the company, any questions on the issue should be directed to the Royal Bahamas Police Force.
MERRI LAURSEN: This is actually on the trip, dancing with his cousin and his aunt and uncle. That was kind of neat to see. These are the kids that were on the cruise ship. This was taken quite a few years ago.
Six months ago, Merri Laursen joined the growing ranks of families left searching for answers when her 20-year-old son Blake was reported missing on a family cruise to Alaska. At home alone inCalifornia, it was via the internet that Merri learned the worst.
VOICE OVER: 20-year-old Blake Kepley was reported missing Friday as the ship stopped in Kexican. After a search covering 350 miles from the air and sea, the coastguard suspended the search just before 4:00pm Saturday.
MERRI LAURSEN: I got on the internet. I read that, you know, the boy went missing, aged 20... Um... And the coastguard had searched 24 hours - that they'd called it off.
Blake had left the cabin at 1:30am and wasn't reported missing until five and a half hours later. But when his family requested that the captain review the footage from the security cameras, they were told that wasn't possible.
REPORTER: Do you believe them? Or do you think some of this footage is conveniently never found?
MERRI LAURSEN: I don't believe them. And I believe that they should have real-time video. I mean, how easy would that be, to have actual timer on your camera?
KEN CARVER, INTERNATIONAL CRUISE VICTIMS: I've got a list that shows about 24 cases...
The fact that cruise-ship crime is an issue at all is largely due to this man, Ken Carver. Along with Jamie Barnett, whose daughter was murdered on a cruise, he's on a mission to bring the cruise lines to account.
KEN CARVER: Unfortunately, somebody going overboard makes the news. Every two weeks, according to reports, somebody's going overboard. But that's only the tip of the iceberg, Jamie.
When Ken's 40-year-old daughter, Merrian, vanished off a Celebrity Cruises voyage to Alaska in 2004, he was stonewalled at every turn as he searched for answers to her disappearance. Turning to private detectives, he managed to track down his daughter's onboard steward.
KEN CARVER: To our amazement, this steward said he reported our daughter being missing daily. But was told , "Forget it. Do his job". It was five weeks before the FBI was ever called on our daughter's case. Then, the FBI didn't do anything. They didn't call in anybody. They should have talked to the steward. We had to spend the money to get to that one person to realise that we were dealing with a cover-up.
Outraged at what he saw as the cruise line's callous disregard for his daughter, Ken took the matter to Washington.
KEN CARVER: The story eventually became the subject of five congressional hearings. Out of all of that came legislation.
SEN JOHN KERRY: I particularly want to thank one of our witnesses this morning, Mr Kendall Carver, who has been vigilant in his efforts to improve safety aboard cruise ships worldwide, and who has done so under very difficult personal circumstances.
What resulted was America's cruise, vessel and safety act - an important first step in bringing the cruise lines to heal after decades spent outside the reach of US laws.
KEN CARVER: I come to you both as a victim and as president of a group called International Cruise Victims, a an organisation for... We're not lobbyists. We're just parents looking for answers to what's happened to our children.
Despite the new laws, there's been little improvement. The FBI still seems reluctant to investigate cruise-ship crime, and Jim Walker says the industry has done little to clean up its act.
JIM WALKER: You have cabin attendants now who are being hired from Third World countries - no disrespect to small cibian islands - that have no databases. You can't track them even if you wanted to. You don't know what you're getting. But you're hiring a 28-year-old man to be responsible for 12-year-old girls' cabin. Mum and dad don't know what's happening. They're at the casino, they're at the show, they're up at the nightclub, and the cabin attendant gets back into the cabin - that's still happening. Those cases are still happening.
While the cruise industry has followed some guidelines, such as installing peepholes in cabin doors, few ships have upgraded their video systems or installed man-overboard alarm systems. And passengers continue to disappear.
MIKE CORIAM: I just can't believe that the international community are letting this go on, really. It's just hard to understand why they let it go on.
MERRI LAURSEN: I look at the water now, and it's beautiful, but my son's out there somewhere. And, you know, he was on vacation. He was happy. This was something he was looking forward to. And he never came home.
YALDA HAKIM: Nick Lazaredes there. Go to our website and let us know what you think of the way the cruise companies have handled the mysterious disappearances. Of course, you can see all of Nick's stories online:
ORIGINAL MUSIC COMPOSED BY