Researchers aboard the exploration vessel Nautilus recently encountered a fascinating sight at a depth of 3,000 meters on the Liliʻuokalani Ridge. They captured footage of what they described as a “yellow brick road” formed by fractured volcanic rock. This unusual formation sits atop Nootka Seamount, an underwater volcano in the Papahānaumokuākea Marine National Monument. This vast area, designated by President Obama in 2016, covers over 582,578 square miles, making it larger than all U.S. national parks combined.
The video segment revealed a dried lakebed made of hyaloclastite rock, which forms during intense volcanic eruptions. As the lava cools and fractures, it creates angular pieces that settle on the seafloor. Interestingly, researchers noted 90-degree angles in the rocks, likely due to the extreme heating and cooling processes that accompany volcanic activity.
This discovery was part of the Luʻuaeaahikiikemu expedition—the first visual survey of these seamounts since a mapping mission in 2021. That mission revealed that the summit depths of these formations were shallower than previously thought, challenging what we knew about Cretaceous-era geology, which dates back 66 to 145 million years.
Despite its vast size, only about 3% of the monument’s seafloor has been explored visually. According to a study published in Science Advances, humans have only documented a minuscule 0.0006 to 0.001 percent of the world’s deep-sea terrain over the past 67 years.
What’s more, this expedition was notable for its inclusion of cultural liaisons from Native Hawaiian organizations. Their involvement reflects a growing acknowledgment of indigenous knowledge in scientific research. The term Luʻuaeaahikiikemu connects to the Kumulipo, a Native Hawaiian creation chant.
The brick-like formations are fascinating from a geological perspective. Lava can create hyaloclastite formations when it interacts with water, either under the sea or when it flows into it. As it cools, the material shrinks and cracks, resulting in these striking patterns.
During the dive, the crew’s reactions were infectious. One researcher humorously referred to it as “the road to Atlantis,” capturing the sense of wonder shared amongst the team.
The researchers also collected crucial samples from the rock surfaces, including basalt coated with ferromanganese crusts. These mineral deposits can provide insights into the microbial communities living within them, essential for understanding and managing the delicate deep-sea ecosystems.
However, the expedition faced some limitations. Visual surveys were limited to paths accessible by remotely operated vehicles (ROVs). The geological ages of some formations remain uncertain and require further analysis of the collected samples. Future research will help piece together the geological history of the Northwestern Hawaiian Islands.
Funding for this mission comes from NOAA Ocean Exploration, with additional support from various government bodies. Researchers aim to review their findings by 2026, focusing on enhancing management strategies for the deep-sea habitats within this remarkable monument.
For more detailed information on Papahānaumokuākea, explore the official National Monument page.
