In 2022, a deep-sea expedition north of the Hawaiian Islands revealed an ancient dried-up lakebed. At the bottom, there appeared to be a paved yellow brick road.
An exploration vessel called the Nautilus had been surveying the Lili’uokalani ridge in Papahānaumokuākea Marine National Monument (PMNM), which is one of the world’s largest marine conservation areas. Only about 3% of its seafloor has been explored. It is 9,843 feet below the surface.
Researchers at the Ocean Exploration Trust were remotely operating the deep-sea vehicle Nautilus to examine the ocean floor when they came across what looked like a “yellow brick road” leading to the “lost city of Atlantis.”
However, it is not an artifact from an ancient civilization. The “road” is actually an example of active volcanic geology. The hyaloclastite rock, a type of volcanic rock, was formed during powerful eruptions when lava flows into water, ice, or watery sediments.
Several eruptions caused the area to heat up and cool rapidly over and over. The temperature at such depths is around 39 degrees Fahrenheit. Due to the eruptions, many rock fragments also settled to the bottom of the ocean.
In one small section of the “yellow brick road,” the volcanic rock closely resembles bricks. Some of the cracks in the rock intersect at 90 degrees and split the path into rectangles. It was remarkable how dry it looked for being so far underneath water.
The discovery wouldn’t have been made without the technological advances of today. Humans have been recording deep dives into the ocean for 67 years. Even in all that time, only a tiny portion of the seafloor has been studied. That’s just how vast the ocean is.
A team of researchers from the nonprofit Ocean Discovery League, the Scripps Institution of Oceanography, and Boston University calculated exactly how much of the seafloor has been explored so far.
According to their estimates, humans have covered between 0.0006% and 0.001% of the seafloor. The percentage range is equivalent to 1,476 square miles of territory, which is slightly larger than the U.S. state of Rhode Island.
Sign up for Chip Chick’s newsletter and get stories like this delivered to your inbox.
Since the discovery of the “yellow brick road,” Nautilus has made multiple trips down to PMNM. It has mapped unsurveyed areas and collected data on the animals and microorganisms there. It also visited the Palau National Marine Sanctuary in the western Pacific in 2024.
Studying the ocean is important because it allows experts to learn more about the marine ecosystem. It’s the first step toward protecting species in the deep sea.
The marine ecosystem also aids in regulating the climate and can even lead to the development of new healthcare solutions.
“Our exploration of this never-before-surveyed area is helping researchers take a deeper look at life on and within the rocky slopes of these deep, ancient seamounts,” said the researchers from the Ocean Exploration Trust.
By Emily Chan
Emily Chan is a writer who covers lifestyle and news content. She graduated from Michigan State University with a degree in... More about Emily Chan
