Of Finnigirt Dr. Jacobsen says: "There are a few legends told about places along this dyke stead, and the spot where it terminates on the south side of the island has been of old a noted place for trolls.
From John Spence, 'Shetland Folk-lore' 1899. (Dr Jakobsen researched language and folklore on Shetland.)
According to Spence, whenever 'Finn' turns up in a Shetland place name it refers to a legendary race of beings, some of whom had descendants with extraordinary powers (such as being able to render themselves invisible, metamorphose into animals, and even understand the corbies - the ravens. They also had control over the weather at sea, and could find things lost at sea, and ride the 'Neugle' water horses.)