Icelanders are very serious about their trolls. In fact, more than half the population accepts the existence of the “Huldufólk” or “Hidden Folk”; supernatural beings that reside in, beneath or behind the rocks and mounds. They decorate homes and gardens. People refer to them with a peculiar reverence, sometimes with a wink and a nod as if to challenge the non-believers. One day in July I visited Arnarstapi, a small …