Global Volcanism Program | Image GVP-10746
Two large cones have been constructed on the NW and NE rims of a roughly 3-km-wide submarine caldera at Nikko. The caldera rim is prominently displayed on the southern side and is largely buried to the north. A smaller cone fomed on the SE caldera floor. Discolored water has frequently been observed above the seamount and hydrothermal venting was documented at the main cone during a NOAA expedition.
Image courtesy of NOAA, 2003 (http://oceanexplorer.noaa.gov/explorations/03fire/logs/mar02/media/nikko.html).
This image is made available as a Public Domain Work, but proper attribution is appreciated.