Underwater volcanoes are hard to sea, er, see. The Axial Seamount is a volcano off the coast of Oregon that just began erupting again. Previous eruptions were “found to be 18,000–76,000 km3 (4,300–18,200 cu mi)”. Just to make things interesting, the volcano also sits on the Juan deFuca fault, part of the Cascadia Subduction Zone – a zone prone to generating 8+ earthquakes and massive tsunamis – just off the navigation entrance to the Columbia River. Just pretending not to panic about it.