For 89 days, Tony Romeo and his team had nothing to show for their three-month expedition to find Amelia Earhart's missing plane.
On day 90, they may have made the discovery of a lifetime. Sonar images from 16,000 feet under the ocean captured what Romeo is "certain" is the key to one of the country's most fascinating mysteries.
"We were frustrated. We were disappointed, and everybody was kind of on each other's nerves," Romeo said. "And then boom, there it is. It pops up on the screen. It's kind of a surreal moment, one we'll always remember."
Romeo took his findings to the Scripps Institute and the Smithsonian, which backed his strong belief that he found Earhart's plane.
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Earhart's plane vanished on July 2, 1937, near Howland Island, an uninhabited island just north of the equator in the central Pacific Ocean.
Her remains or her craft were never found, which fueled endless speculation and theories that ranged from crashing on a different island to conspiracies and alien abductions.
The most commonly accepted theory is that she ran out of fuel.
"She would have brought it down as gently as possible on the surface of the water, and then basically tried to climb out of the hatch, which is right above the cockpit," Romeo explained.
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As he spoke, he used the prop plane to imitate the motion and pointed to where the hatch would have been. Then he put his fingers on the two front engines.
"The airplane would have probably fairly quickly nosed over (because of the weight) and then just spiraled all the way down the seafloor," the Air Force veteran said.
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They found what was potentially the missing craft about 16,000 feet under the ocean. In comparison, the Titanic wreckage is about 12,500 feet underwater.
"At 16,000 feet, where we found this, the plane would likely be in very good shape and preserved very well because of the temperatures, the pH levels and the oxygen-free level in the water," Romeo said.
There are also distinctive features on Earhart's plane that appear to be seen in the blurry sonar images that he explained during Tuesday's visit with Fox News Digital.
"The tail, you see those twin vertical stabilizers," said Romeo, with his fingers on the prop plane. "The terrain on the seabed is flat and sandy, so to see something protruding above the seabed, makes it immediately suspect.
"And three, the size of the aircraft falls right within the dimensions that we'd expect for her aircraft. And there's no other known airplane crashes in the area."
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Romeo said it's "always possible that something weird happened," but the Scripps Institute and the Smithsonian agree that he found the wreckage of a downed plane and, in theory, fits Earhart's missing craft.
Dorothy Cochrane, an aeronautics curator at the Smithsonian’s National Air and Space Museum, told Fox News Digital that Deep See Vision's sonar image is "intriguing" and the location matches the most likely spot of the infamous wreck.
"Earhart’s and Noonan’s disappearance near Howland Island is one of the great mysteries of the 20th century and continues into the 21st century," Cochrane said.
"Earhart was a very famous pilot and woman of her era, and her round-the-world flight was closely followed by the press, newsreels and the public.
"Locating her Electra would be headline news today — solving this great mystery and then allowing us to focus on her pioneering aviation career and her contributions to aviation and women’s issues."
That's why it's vital to continue the mission. She implored Romeo's team "to continue to research it and gather detailed photography for actual object identification."
And that's his next step. They're in the planning phase right now, he said, but he hopes to return this year.
"The next step is confirmation of the plane," Romeo said.
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That will be done with high-tech, underwater vehicles to take clear pictures and "figure out how it's sitting, and maybe some do some analysis on whether it's structurally sound or if it's become fragile."
"It may look like almost one of the wings is bent down, or maybe it's upside down and one of the wings is caved in," Romeo said, "so we have a bit more to learn about how the aircraft is actually sitting on the seabed."
Earhart was one of the greatest pilots of her time, and broke the glass ceiling in the feminist movement.
Coming from an aviation family, Romeo was always drawn to her incredible story and century-long mystery.
After graduating from the Air Force Academy and serving in the military, Romeo dabbled in law and built a real estate company, which he sold to fund Deep Sea Vision and the expedition.
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"My dad flew for PAN AM. And for many years, my brother was a pilot, my sister is a pilot, and I went to the Air Force Academy," Romeo said. "So this is story is one I grew up hearing about.
"And so, you know, at the point where I was getting out of commercial real estate, it was a perfect intersection in my life to try something new."
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And he may have solved one of the most perplexing unknowns in American history.
Fox News Digital's Emmett Jones contributed to this report
