Almost a year after the Hunga Tonga Hunga Ha'apai eruption, where an undersea volcano sprang forth from the deep - quite spectacularly, we have new footage of another undersea eruption. Fukutoku-Okanoba, off the coast of Minami Iwo, started to erupt yesterday (or, at least, erupt enough to manifest a plume out of the ocean). A Japanese coast guard vessel was able to capture the plume on video as it reached 100 m / ~300 feet. The plume appears to be dominated by white steam along with some grey ash mixed in. Additional footage shows the water stained brown/tan with ash and volcanic debris from the eruption as well.
Fukutoku-Okanoba is actually a quite active submarine volcano, last erupting in 2005. The sea is often discolored near the volcano and a number of ephemeral islands have formed due to its activity over the last 100 years - my favorite being Shin-Iwo-jima, or "New Sulfur Island" in 1904. Most of the eruptions appear to be VEI 0-2 based on what manifests at the surface, however the 1904 eruption was VEI 3, producing significant andesitic (intermediate) ash and lava. The summit of the volcano lies only 14 m / ~50 feet below the ocean surface.