Researchers returned to Oahu this week with new, vivid maps of the seafloor in the deepest reaches of the marine national monument in the Northwestern Hawaiian Islands. They also brought back some surprise findings that could guide the exploration of that protected area for decades to come.

Using sonar technology, a science team aboard the privately funded Falkor research vessel said high-resolution images revealed 18 undersea mountains, or seamounts, that previously had not been mapped in the northwestern corner of the Papahanaumokuakea Marine National Monument. That’s despite some of those mountains’ peaks reaching within 150 feet of the ocean surface.

"We don’t think they’re Hawaiian," Christopher Kelley, the 36-day expedition’s chief scientist, said Friday,

The seamounts, Kelley and the other expedition scientists believe, predate the volcanoes that formed the Hawaiian Islands by some 60 million years. They likely originated farther east in the Pacific and then made their way to the Hawaiian Island chain over millions of years by way of the Pacific tectonic plate, Kelley said.

Some of the seamounts are flat-topped, indicating that they once were near or above the ocean surface — despite their current location some 1,400 meters below the surface, officials said.

The "misconception is that everything here on the seafloor in the archipelago was created in Hawaii," said Kelly, a program biologist with the University of Hawaii’s Undersea Research Laboratory. "We think that’s wrong."

The findings came amid the first trip to the monument for the Falkor, a 272-foot-long mobile, globe-trotting research ship. It’s funded by the Schmidt Ocean Institute, a science venture created by Google Executive Chairman Eric Schmidt and his wife, Wendy.

The ship’s science team mapped some 23,000 square miles of seafloor in the northern end of the monument — a zone three times as large as the land area of all main eight Hawaiian Islands put together and just 17 percent of the total monument, officials said.

"Our goal was to map everything down to 4,000 meters … get them completely done so we could really see what the whole structures look like," Kelley said, recapping the voyage’s results from the science control center, a high-tech room in the belly of the Falkor.

There’s also a good chance that the seamounts revealed in Falkor’s sonar imagery serve as habitats for deep-sea coral and sponges — the "engineers that form habitat for all kinds of other things," said Daniel Wagner, a National Oceanic and Atmospheric Administration research specialist with the monument and Falkor crew member.

"There’s a lot of species here that aren’t found anywhere else on the planet," Wagner said. The formations — roughly scattered around Midway, Kure, Pearl and Hermes atolls — could be home to undiscovered marine species, Wagner added. The only way to know for sure will be to eventually dive there via submersible or send a remotely operated vehicle, he said.

However, the mapping did help researchers select areas in shallower, scuba-diving depths for exploration in an upcoming expedition planned for September, Wagner said.

"All of these programs rely on good maps of the area. Because it is so big, you really can’t just go out there and study everything. You have to focus and target your resources, and good maps are one way of doing this," he said.

When she visited Hawaii in November, Wendy Schmidt said her institute aimed to help fill the void created by dwindling federal research budgets at a time when the oceans "are under attack" and in dire need of study.

"The maps generated from this will probably be used for decades, if not centuries," and they’ll be made available for the public to access freely, Wagner said.

Understanding how marine life interacts with these rocky formations could usher in ways to better protect species in regions outside the monument, especially if commercial undersea mining ever becomes a reality, Kelley said.

"We have a chance to actually do it right here, because (undersea) commercial mining has not taken off, and that’s the race," Kelley said. "Let’s not ignore this environment. Let’s find something out about it so we don’t mess it up."

The Falkor plans to return to the monument next month to map another stretch roughly the same size, Wagner said. If all goes well, when they’re done about a third of the monument’s undersea floor area will be mapped with high-resolution imagery.