First, a little background on Loihi. This seamount, which lies about 35 km off the southeast coast of the Big Island, is the youngest volcano in the Hawaiian chain, although it will be at least another 10,000 years before it actually reaches the surface and starts developing black sand beaches for tourists to toast themselves on. Loihi has a summit caldera with cones and pit craters, and its eruption style varies from explosive (the subject of this article) to effusive (pillow lavas, which are mentioned in the discussion about vesicularity). When I first came to grad school, I would have thought of a submarine eruption as passive extrusion of pillow lavas, similar to the videos you can see on NOAA's Ocean Explorer website. This isn't always the case, however. While it's been fairly obvious that volcanoes just reaching the ocean's surface can erupt in an explosive and spectacular fashion, it hasn't always been clear that underwater volcanoes are capable of the same thing.
Schipper, C., White, J., Houghton, B., Shimizu, N., & Stewart, R. (2010). "Poseidic" explosive eruptions at Loihi Seamount, Hawaii Geology, 38 (4), 291-294 DOI: 10.1130/G30351.1