Transcript for Death Down Under: What Really Happened?
An hour ago. -- A weakened to their dream honeymoon Tina and Gabe Watson -- doing a newlywed breakfast on the -- of the spoil sport. Where their first scuba dive of the -- Did Tina seem nervous. Not to Michigan coming -- excited I was excited we were ready again. Other passengers aboard the boat have logged hundreds of -- he has more than fifty including a rescue diver certification. But Tina only has a handful of -- all of -- what is essentially a shallow pool in this Alabama quarry. It is a far cry from the ocean waters of Australia especially for a novice diver. Did he ever say to you you should have an orientation I was whenever kinds. I never knew the -- had not been in the ocean before. You didn't know she'd never been -- of the white you know back to you ever ask her capture ocean -- go now. -- Now that -- -- is never -- and it's astonishing to me that you know that. So how difficult do you think these guys were going to be a kind of figured world vacation they're they're going to be. Very easy home. Nice pretty dobbs. But. Even Tina aren't in Alabama anymore fifty feet below a challenging drift dive over the back of the SS -- -- -- 350 foot steel steamer that sank during a storm in 1911. Taking 120 souls to the bottom of the ocean. Nicknamed the Australian Titanic and the shell of the ship has been since transformed into a vibrant garden of corals marine life. And on that day when another challenge for a novice diver and the current. The crew warns them this is an advanced or red dot yeah did you know and now. -- you ask somebody. That never purchased a man. We -- on our honeymoon we just really thought they were there to take care of us. The Great Barrier Reef. Yeah probably sharks center and lots of strong currents you didn't know winning it back before you on this -- now. To understand what happens next you need to know a little bit about -- each year. -- -- suit up on the desk wearing a wet suit hinges a dive mask and an air tank. Like all divers Tina and -- also have an important item called a boy and -- compensate -- nest NBC for short. Its purpose is to help the diver and go down or up. With the -- -- one -- -- the best to place another let the air -- allows the diversion dissent. And something else which would prove to -- little later Ron. -- -- too -- dive computer which allows him to monitor Howard Dean he's going and how much air he's used. But as soon as he enters the Watergate says the computer signals something is wrong thing it was meaning. I don't look innocent guests more from. David Tina resurface he realizes the battery in -- transmitter is backwards fixes it and and to return to the water. The couple plans to -- fifty feet down a line anchored to the rag then drift along with the current from one end of the ship. To the other and ending here at a second line. And -- and turning to the surface. -- soon the reality of that strong current -- game. You know we're moving quite it was pushing yet it was it was pushing us along some divers find this very unnerving to -- it struck. It was definitely not. What I was expecting. Moral decision as they -- -- -- gave says -- signaled that she was uncomfortable she's kind of and what -- Danone and does that back towards Hillary came from an -- back -- up because this is a signal to go now like hitch hiking kind of deal. -- -- my right hand and geographic. Both started swimming. Backwards but we weren't really making. So what did you do them and turned to her. Grab -- months later hose and motioned to her puts -- -- and we'll just we'll start floating up. Good news -- but didn't happen but one theory -- The wrong button on the BC releasing her from her -- making nursing -- in that moment gates has he had only one box where. The trouble. So I reached out. And cannot just colder in and started heading back to -- -- -- but I remember trying to -- you know swim swim team a swim you really scared -- scared to death but. -- -- -- -- -- -- -- -- I'm mask who got what turned off to the -- -- -- -- Just let go with Tina to put his mask back. And it turned around the world. Down envelope. I don't know ten. Feet -- what was she doing. She was sinking. And face she was face and she had her arms -- reaching out for me to rattle them. Did you try -- a time just turn on my head in -- debut he's bound to see -- -- A lot of -- country and I'm sorry I got to -- Angela. He says he quickly swam the fifty feet to the surface -- -- -- that would later be questioned. Cut the services to -- with this team has gone down hill has gone down. Have to ask the question that so many people asked how could you leave -- -- you to leave her I don't think I was making rational -- that the point. I don't know what I would have -- -- -- -- -- -- do you think you -- -- to. Problems. Yeah -- single guys already in the water's oxygen and -- to rescue her and and then at this moment. A haunting image that would define this story comes from another -- snapped this photo of his wife. And unwittingly captures Tina's body on the ocean floor. When you know that somebody had found -- -- and brought her to the surface some guy came over to me and said she's going to be okay. Only Tina wasn't okay. Crew members and fellow passengers try for forty long minutes to resuscitate her eight is comforted by other divers and -- built -- buying. And -- looked out the window but. -- home to secure. And just a losses and then -- out. At that moment -- didn't try to get to that other boat the decision to stay where he was would later strike people as -- want. And for people who might not understand why you -- -- You would say. That's because council -- can handle. I don't I don't ever want to see. What I'm about what's being -- -- that ever. Shocking news from a fellow passenger. He's walked up to -- and said. It's hard but -- had an interest that -- -- sort of. I was that is. But two other divers -- Snyder and Doug Millsap are already suspicious. Rejecting -- claim that he was unable to bring Tina to the surface. Juniper the other divers on your saying they gave that's BS I don't remember -- you better come up with a different story. This seemingly distraught young man who left boards a newly -- returns that night Millwood aware. His mother Glenda flight to Australia and his by his -- five days later as police questioned -- about the events of that morning. -- -- down I was kicking them as fast I was -- It is one of many statements that would generate questions for the authorities and -- how did a perfectly healthy woman with the -- building here adrenaline. Did Davis and looking for help as fast as he claimed he had. At what point that the questioning -- suspicion. That he -- in fact. Planner the first piece of evidence that they look at what's that computer I believe that that piece of evidence and what they thought was catching game on the line put the blinders on their investigation.
This transcript has been automatically generated and may not be 100% accurate.