Sycamore Knoll: The Mysterious Underwater Structure Off the Coast of Malibu

The Formation

Sycamore Knoll sits approximately 6.6 miles off the coast of Malibu, California, at geographic coordinates 34°1'23.31"N, 118°59'45.64"W, roughly 2,000 feet below the surface of the Pacific Ocean. It is nearly three miles across and two miles wide, covering almost five square miles — comparable in area to Culver City. The feature has a distinctly flat, table-like top that researchers and casual observers have noted appears unusually regular for a natural underwater geological structure.

The UFO and USO Connection

For decades before the formation gained wide attention, residents of Malibu and the Santa Monica Mountains reported unusual sightings along the Malibu coast — luminous objects skimming the water's surface, objects entering and exiting the ocean at speed, and objects appearing to hover at low altitude over the water near Point Dume. MUFON investigator Preston Dennett, whose multi-year investigation of the broader Southern California coast was published in books and in Fate magazine, formally documented the Malibu anomaly in a 2006 article titled "Is There an Underwater UFO Base off the Southern California Coast?" Drawing on firsthand testimonies from Navy, Air Force, Coast Guard, police officers, lifeguards, and local residents, Dennett presented what he described as a compelling pattern of transmedium craft activity — objects capable of moving through both air and water — concentrated around this specific location.

The National UFO Reporting Center Data

The National UFO Reporting Center (NUFORC), which has tracked U.S. sightings since 1974, has logged a notably high concentration of reports from the Malibu coastal area, including specific accounts of luminous objects emerging from and submerging into the ocean. In one widely cited account submitted to the center, a witness described "a massive, cathedral-shaped structure — multiple pointed edges all glowing brilliantly white, heading straight into the ocean."

Military Witness Accounts and Congressional Interest

Investigative journalist Jeremy Corbell, working with veteran journalist George Knapp, released footage in 2023 purportedly taken aboard a U.S. Navy vessel showing a self-luminous, wingless, tailless craft rising from the Pacific Ocean. An active-duty Navy Combat Information Center (CIC) operator who witnessed the event stated that the object rose from the ocean on its own. The incident was aligned by Corbell with a pattern he described as recurring in Warning Area 291, a military airspace designation off the Southern California coast encompassing the area near Malibu. At Congressional UAP hearings, Colorado Congresswoman Lauren Boebert directly asked military witnesses: "Are there any accounts of UAPs emerging from or submerging into our waters which could indicate a base or presence?" The question was met with responses confirming that such reports existed in the record.

The Google Earth Disappearance

Sycamore Knoll was long visible on Google Earth, and numerous researchers and journalists used its satellite coordinates to study and document the formation. Beginning in late 2024, the feature disappeared entirely from Google Earth — replaced with a blurry, featureless patch of ocean. UFO researchers and satellite monitoring groups flagged the change publicly; Reddit threads and investigative outlets confirmed the disappearance. As of early 2025, the formation remains invisible on Google Earth but viewable through other mapping platforms including marine navigation and fishing charter applications.

The Scientific View

USGS earthquake geologist David Schwartz, who published a 2009 paper on Southern California's offshore geology, has maintained that Sycamore Knoll is entirely natural. Schwartz concluded it is the surface expression of the Dume thrust fault, part of a larger fault system in the region. The formation's unusually flat top, he argued, is consistent with geological processes associated with thrust fault movement, where one crustal plate overrides another, creating sharp elevation changes in the sea floor.