The E/V Nautilus expedition to the Liliʻuokalani Ridge (Papahānaumokuākea Marine National Monument) uncovered a yellow, brick‑like pattern in 2022. Geologists identified the feature as fractured hyaloclastite — volcanic rock fractured into near‑90° blocks by heating and cooling after repeated eruptions. The finding, captured on expedition footage, underscores how little of the deep seafloor humans have explored and points to new geological and biological research opportunities.
Scientists Find a Deep‑Sea 'Yellow Brick Road' — Volcanic Rock Cracks Into Brick‑Like Tiles
Bricks appearing on the seafloor
An expedition surveying a submarine ridge north of the Hawaiian Islands uncovered an unexpected sight in 2022: a yellow, brick‑like pattern on the deep seafloor that resembles an ancient, dried lakebed.
The exploration vessel E/V Nautilus encountered the formation while mapping the Liliʻuokalani Ridge inside Papahānaumokuākea Marine National Monument (PMNM). The discovery was captured in live and recorded footage released by the expedition, which drew surprised reactions from the science team.
Red pencil urchin (Heterocentrotus mamillatus) at Papahānaumokuākea Marine National Monument. (US Fish & Wildlife Service - Pacific Region's/CC BY 2.0/Wikimedia Commons)
"It's the road to Atlantis," one researcher exclaimed on the radio. "The yellow brick road?" another responded. "This is bizarre," a team member added.
Geologists identified the feature as a fractured flow of hyaloclastite, a volcanic rock that forms when explosive, high‑energy eruptions produce many hot fragments that settle and weld on the seafloor. Cooling and repeated eruptive events produced a hardened, "baked" crust that has fractured into nearly right‑angled blocks in places, producing the brick‑like appearance.
Why It Looks Like Bricks
The nearly 90‑degree fractures likely result from heating and cooling stresses at the margin of the flow after multiple eruptions. In one small patch on the summit of the Nootka Seamount, the pattern is especially striking: tight, rectangular fractures that give a tiled effect.
The researchers found the discovery of a 'yellow brick road' to be very unusual. (The Ocean Exploration Trust/E/V/Nautilus/YouTube)
Depth, Scale, and What It Means
The Nautilus team surveyed parts of the ridge that sit more than 3,000 meters (about 9,843 feet) below sea level; other sections nearby lie under roughly a thousand meters of water. The discovery highlights how little of the deep seafloor has been visually explored. A 2025 analysis estimated that humans have imaged only about 0.0006–0.001% of the deep seafloor — an area roughly equivalent to a small U.S. state.
Visual surprises like the hyaloclastite "yellow brick road" make abstract statistics tangible and point researchers toward new geological and biological questions on these ancient submerged mountains.
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"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," researchers from the Ocean Exploration Trust said, noting that ongoing surveys will expand knowledge of both geology and ecosystems in PMNM.
You can view highlights from the 2022 E/V Nautilus expedition footage to see the discovery firsthand. An earlier version of reporting on this discovery appeared in May 2022.
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