Planet Earth - Submarine volcanoes: The hidden fiery vents beneath Earth's oceans

Deep beneath the oceans, submarine volcanoes release magma through underwater fissures and vents. Scientists estimate that more than one million submarine volcanoes exist on Earth, though most are extinct. The vast majority sit along mid-ocean ridges, where tectonic plates form, generating roughly seventy-five percent of the magma output on Earth. Around seventy-five thousand underwater volcanoes rise over one kilometer above the seafloor. Near these volcanic features, hydrothermal vents frequently appear, supporting dense and vibrant biological communities.

Source: Wikipedia