One might guess that the foulest-smelling flatulence in the animal kingdom would belong to something of substantial size -- an elephant, camel or hippopotamus, perhaps.
"Of all the gastro-releases I have had the pleasure or displeasure of experiencing, the sea lion is the one that will clear the area the quickest," Schwartz said.
Schwartz told podcast producer Andrew Norton there's a perfectly good scientific explanation for why seal lion farts are so terrible.
"Keep in might that sea lions eat a wide variety of fish and squid species," he said. "Fish, in general, can get pretty odiferous pretty quickly. Now put it through the chemical changes that goes on in a stomach and blow that out the other end, you have an idea that it's a very powerful, pungent odor."
Asked to describe the stench, Schwartz said, "I don't think there's really any other odor on the planet that could do it justice to describe it to a citizen who's never experienced it."
Listen to the full episode of Greenpeace's "Completely Optional Knowledge" below.