What That ‘Yellow Brick Road’ Under The Pacific Ocean Really Is

A quirky science story emerged from the ocean depths in 2022 and it’s now circulating online again. A team of ocean explorers spotted what looked like a “‘yellow brick road’ to the mythical city of Atlantis” while exploring the ocean floor in the Papahānaumokuakea Marine National Monument in the Pacific Ocean west of Hawaii. The formation’s resemblance to a human-built road captured the public’s imagination, but it isn’t an artifact from a long-lost civilization that was swept under the waves.

The video came from a remote-operated vehicle piloted by the crew of the Exploration Vessel Nautilus. The research vessel is operated by the nonprofit Ocean Exploration Trust. OET has active outreach and public engagement components to its work, so the group often livestreams the E/V Nautilus adventures. Highlight videos from the ROV dives often show off unusual sea animals, like this rare deep-sea jelly.

The E/V Nautilus team originally posted a highlight video in April 2022 showing off some intriguing geologic features at the Liliʻuokalani Ridge seamounts in the national monument. Seamounts are underwater mountains.

Casual viewers might miss what’s really going on with the road-like formation. “What may look like a ‘yellow brick road’ to the mythical city of Atlantis is really an example of ancient active volcanic geology,” the team wrote at the time. The original video features enthusiastic live commentary from researchers who were wowed by the appearance of the rock and likened it to the yellow brick road from The Wizard of Oz. They described it as “bizarre,” “cool” and “crazy.” The orderliness of the formation along with a public appetite for strange sea discoveries turned the funky rocks into an online hit.

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The story’s reemergence in 2024 prompted the Nautilus team to address the video anew. “Our 2022 ‘yellow brick road’ video is making the rounds in the news cycle again, so we wanted to share the real story behind this fascinating geological feature: a fractured flow of hyaloclastite rock that happens during high-energy eruptions,” the group wrote on X on Nov. 7. Hyaloclastite rock forms when lava flows into water, ice or watery sediments. It’s a common occurrence with undersea eruptions and can often create angular forms.

OET also posted a video on X explaining how the brick-like formations are likely caused by heating and cooling stress from multiple eruptions.

E/V Nautilus has made multiple visits to the Papahānaumokuākea Marine National Monument to map previously unsurveyed areas. Besides taking a literal deep dive into the geology of the area, the vessel also collected data on the animals and microorganisms that call the seamounts home. “These studies will help provide baseline information on the living communities of seamounts which can inform management and conservation measures,” the team said. There’s much more to discover. Papahānaumokuākea covers over 582,500 square miles and is one of the largest marine conservation areas in the world.

E/V Nautilus hasn’t slowed down since the yellow brick road. It’s currently visiting the Palau National Marine Sanctuary in the western Pacific on a mission to explore and map the seafloor. Stay tuned for more wonders from the deep.