Pillow Lava Formations in the Deep Sea of the Marshall Islands
What happens as lava erupts from the seafloor in the deep? On slopes with moderate steepness, lava often flows in such a way that it creates what scientists call pillow lava formations. In this video filmed by ROV Hercules while exploring Ļewōnjoui Seamount in the waters of the Marshall Islands, Dr. Val Finlayson explains the full landscape of these fascinating geological formations. Pillow lavas are formed when hot magma erupts and the outer layer quickly cools in the surrounding chilly seawater. The persistent ooze of lava in the molten interior bubbles up distinctive, rounded shapes behind the chilled exterior. Large eruptions form huge flows as pillows break open, forming more mounds downslope, resulting in huge solidified rounded pillow piles.
The NA174 expedition to explore the deep sea of the Republic of the Marshall Islands is funded by NOAA Ocean Exploration via the Ocean Exploration Cooperative Institute.

Deep-Sea Habitats of the Marshall Islands
The Republic of the Marshall Islands is an atoll-based country of over 1,200 islands surrounded by 2.13 million square kilometers of ocean, the vast majority of which has never been mapped or surveyed.