Cameron has completed 33 dives to the wreck of the Titanic.
He said he was on a ship on Sunday when the sub went missing, and did not hear about it until Monday.
When he learned that the sub had lost both its navigation and communication at the same time, he said he immediately suspected a disaster.
“I felt in my bones what had happened. For the sub’s electronics to fail and its communication system to fail, and its tracking transponder to fail simultaneously – sub’s gone.”
The director went on: “I immediately got on the phone to some of my contacts in the deep submersible community. Within about an hour I had the following facts. They were on descent. They were at 3500 metres, heading for the bottom at 3800 metres.
“Their comms were lost, and navigation was lost – and I said instantly, you can’t lose comms and navigation together without an extreme catastrophic event or high, highly energetic catastrophic event. And the first thing that popped to mind was an implosion.”
On Thursday, an official from the US Navy told the BBC’s partner CBS News that the navy detected “an acoustic anomaly consistent with an implosion” shortly after the Titan lost contact with the surface.
The official said the information was relayed to the US Coast Guard team which used it to narrow the radius of the search area.
Cameron told BBC News the past week has “felt like a prolonged and nightmarish charade where people are running around talking about banging noises and talking about oxygen and all this other stuff”.
“I knew that sub was sitting exactly underneath its last known depth and position. That’s exactly where they found it,” he continued.
He added that once a remotely controlled underwater vehicle was deployed on Thursday, searchers “found it within hours, probably within minutes”.
