The most famous submarine volcanoes are those that lead to the formation of new islands, such as the eruption of Surtsey in Iceland in the 1960’s. However, many more volcanic cones spend their entire lives below the waves. Unlike their terrestrial counterparts, the activity at these volcanoes cannot be monitored using satellite technologies that today can detect changes in elevation to a cm scale on an almost daily basis. Within the ocean this job is much more difficult and so we know comparatively little about the pattern of activity on fully submerged volcanic cones. We have recently completed a study of Kick-em Jenny volcano in the Caribbean and show it to have periods of cone growth and flank collapse. These processes are similar to the much-better studied terrestrial examples nearby such as Soufriere Hills, Montserrat.