An expedition to a deep-sea ridge in Papahānaumokuākea Marine National Monument (PMNM), just north of the Hawaiian Islands, in 2022, discovered an ancient lakebed paved with what appears to be a yellow brick road. The discovery was made while the exploration vessel Nautilus was surveying the Liliʻuokalani ridge in PMNM, which is one of the world's largest marine conservation areas and only covers about 3 percent of its seafloor. The lakebed was identified as a fractured flow of hyaloclastite rock formed in high-energy eruptions. Researchers believe the discovery could help scientists learn more about Earth's hidden geology.