American Samoa



Seamounts are underwater mountains formed through volcanic processes. Vailulu’u Seamount in National Marine Sanctuary of American Samoa is an active underwater volcano that was first discovered in 1975. Starting at a depth of 16,000 feet at the base and rising to about 2,000 feet beneath the surface, Vailulu’u Seamount is still growing and could eventually reach the surface. Benthic marine invertebrates such as sponges and octocorals attach to the bare volcanic rock, like this pillow lava, and the hydrothermal vents support unique communities of crabs, shrimp, isopods, and eels.

volcanic rock underwater
Photo: NOAA