More natural polluter's...Nature seems to be it's own worse enemy but CC is Anthropogenic? Oh and these exist on the Atlantic side as well.

And what they have found is eye-opening. Since the first evidence of underwater methane was discovered in the late 1980s, only about 100 "seep sites" had been identified along the Northwest coast through 2015. They often were discovered by accident, when fishermen would spot anomalies on their fish-finders that turned out to be acoustic reflections of the bubbling methane gas.