For 15 years, the Swedes thought sounds from the sea were Russian submarines invading their territory. They regularly investigated, sending subs, boats and helicopters - at great expense - only to come up empty-handed. Upon investigation by a biologist, the noise was discovered to be farts* from fish. It seems the Swedes were having herring problems. *aka trumps
Remember the South Park episode, "do you like fish sticks? do you like to put them in your mouth?" Lol, sorry.