Submarine volcanic systems form new oceanic crust, host unique chemosynthetic ecosystems, concentrate rare metals, and provide a conduit for chemical transfer from the Earth's interior to hydrosphere. Although our understanding of submarine volcanoes has been historically limited due to their relative inaccessibility, recent observations from active systems provide valuable opportunities to address key open questions in submarine volcanology. This thesis provides new insight into submarine volcanic processes using observations and samples from the 2011 Axial Seamount eruption, the 2012 Havre Volcano eruption, and the Mid-Atlantic Ridge near 14°N. In Chapter 2, I develop best practices for quantifying vesicle textures and reconstructing total CO₂ concentrations in mid-ocean ridge basalts (MORB).