A subaqueous volcano is a volcano that erupts beneath the surface of a body of water, such as an ocean or lake. These volcanoes are significant in volcanology for understanding the interactions between magma and water, the formation of pillow lavas, and the development of hydrothermal vents.
Reference: Fisher, R. V., & Schmincke, H.-U. (1984). “Pyroclastic Rocks.” Springer.