Nikko submarine volcano, approached from the south and circling around the two summit cones. The western cone is known to have an active hydrothermal system. Depths range from 383 to 2705 meters (1256 to 8872 feet). The EM300 bathymetry data (~25 meter resolution) are overlaid on SeaBat data (~50 meter resolution). Bathymetry data are 2.5 times vertically exaggerated. SeaBat data are courtesy of Ko-ichi Nakamura, National Institute of Advanced Science and Technology, Japan. Fly-through movie courtesy of the NOAA Vents Program.