We know for sure that there are deposits of natural gas in the earth. In theory, natural erosion might eventually allow one to escape on its own. However, it's not at all clear why this would happen on the bottom of the ocean, an environment more favorable to deposition than erosion.
At any rate, if I understand the article, methane is laying around already exposed on the sea floor in semi-stable hydrate form, just waiting for some odd event to turn it into a huge gas bubble. If that's true, there's more untapped energy out there than we thought. The problem is that someone should have put the whole business on a more solid observational basis by this late date than seems to be the case.
Hmmm, what did you say about the bubble?
Whale farts!