During Iceland's Viking Age, a volcanic eruption formed a lava tube, which became a cave known as Surtshellir. Fast forward more than a millennium and a researcher from Brown University heard stories of tourists visiting a Viking Era site inside the cave and taking away bones they found there. What does the site tell us about Viking culture, Norse Mythology, and folklore? We'll speak with Kevin P. Smith to hear what he found when he descended into the cave of Surtur.