Washington scientists guessed that mysterious mounds hundreds of feet below the surface of Hood Canal were deposited by Ice Age glaciers or built up by natural gas seeps or geothermal vents.
After taking a closer look with a remote control camera they have another theory.
No, not space aliens. Underwater landslides.
There are two dome-shaped mounds, each more than 100 feet high and more than 1,000 feet wide, on the bottom at the south end of the canal near Lilliwaup. Scientist with the Department of Natural Resources and Fish and Wildlife Department used a submersible vehicle in 2008 to take a closer look.
They decided the mounds were created by underwater landslides of sediments that had built up at the mouths of two small rivers.
