I Saw A Willow 'O Wisp?

According to wikipedia, will-o'-the-wisp was an evil blacksmith who convinced after he died convinced saint peter to give him a second chance but he didn't change. The devil gave him a lantern and he was forced to walk the earth for eternity using his lantern to lure people to their death in the swamps. When I was reading this story I was reminded of the origin story of the jack o' lantern maybe there is a connection. If you want a more scientific explanation it could be swamp gas.