Exploring the Slope of Vailulu'u Seamount

While many dives during the E Mamana Ou Gataifale II expedition (NA165) explored the hydrothermally active caldera of Vailulu'u Seamount, our Corps of Exploration set our sights on understanding more about the entire underwater mountain. The team, in two dives, explored the deeper slopes of Vailulu’u, from 1500m to the caldera rim above 600m, for the first time since 2005. 

From sea cucumbers to sponges and corals to crustaceans, the dive provided chances to see a wide variety of wildlife, including anglerfish like the fan-favorite Chaunacops spp. and impressively-patterned juvenile batfish “rock climbing” a volcanic talus slope. This seamount provides the unique opportunity to study a volcano in it’s early life, estimated to have been erupting only over the last 300,000 years. Check out the winding lava formations like the volcano pillar left behind as fresh lava erupted into cooling fractures in the slope! Along the ascent, the team also discovered a new hydrothermal vent gurgling shimmering warm water at 651 m. With onboard sampling capability from the Woods Hole Oceanographic Institution’s SAGE (Sensor for Aqueous Gases in the Environment) instrument, the team was able to measure vent fluids to understand the dissolved gasses rising from the slope. Travel with us on the first dive on the north slope of Vailulu'u and enjoy some of the best moments from this special underwater landscape inside the National Marine Sanctuary of American Samoa. 

The E Mamana Ou Gataifale II expedition was led by Ocean Exploration Trust and funded by NOAA Ocean Exploration, NOAA Office of Marine and Aviation Operations Uncrewed Systems Operations Center, and the Bureau of Ocean Energy Management via the Ocean Exploration Cooperative Institute in partnership with the National Marine Sanctuary of American Samoa and with support from Woods Hole Oceanographic Institution and Air/Sea Heritage Foundation.