Axial Seamount off Oregon's coast is the most active volcano in the Pacific Northwest, about 300 miles offshore and just under a mile beneath the ocean waves.

An undersea volcano off Oregon’s coast will likely erupt in 2025, scientists say. Known as Axial Seamount, it’s the most active volcano in the Pacific Northwest – though one most people haven’t heard of because it lies about 300 miles offshore and just under a mile beneath the ocean waves.