Underscoring how much of the Earth remains mysterious, scientists have located "thousands" of previously unknown underwater mountains, known as "seamounts," reports LiveScience. The discovery, announced in this month's Science journal, was a joint effort between a European Space Agency satellite and one from NASA that used high-tech imagery and gravity mapping to find the peaks, which rise a mile or more off the seafloor, the BBC reports. And because they're still analyzing the data, researchers think there may be even more of the topographical treasures. "We may be able to detect another 25,000 on top of the 5,000 already known," says one of the scientists involved with the project. The ocean's deepest parts remain a mystery—as evidenced by the logistical issues during the search for still-missing Malaysia Airlines Flight 370, as the BBC notes—but the Jason-1 and CryoSat-2 satellites worked together to bounce radar signals off the Earth to detect topographic "dips and peaks."
The discovery is important to conservation scientists—"wildlife tends to congregate" near the mounts' peaks, notes the BBC—as well as to researchers who study seafloor makeup to determine water current and heat-transfer patterns. So how come we've never spotted the mountains before? A release from the Scripps Institution of Oceanography cites "drastically improved remote sensing instruments" and new data combined with old. "You may generally think that the great age of exploration is truly over; we've been to all the remotest corners of continents, and perhaps one might think also of the ocean basins," a University of Sydney professor tells the BBC. "But sadly this is not true—we know much more about the topography of Mars than we know about the seafloor." (Tons of plastic in the ocean seems to have disappeared, and that's probably not a good thing.)