Photos Descending Trident Volcano in Katmai National Park (Alaska, USA, 2012). Summit caldera of Katmai Volcano, formed in 1912 during the largest measured volcanic eruption in the 20th century (Alaska, USA, 2012). OASIS expedition team on board the R/V Atlantis. The expedition surveyed a 160 km-long chain of submarine volcanoes in the Pacific Ocean to investigate how they were formed. Click here to learn more about our expedition (8°N, 107°W, 2016). Before we got onboard HOV Alvin to dive to ~2,700 meters below the ocean surface to collect samples of erupted lava. Click here to check out what we saw during our dive (8°24.69’N, 104°50.35’W, 26 Nov 2016).