What is "trollfjord"

The Trollfjord (Trollfjorden) is a 2 km long sidearm of the Raftsund, is being claimed (as of 2016) to lie within one of the following two of Norway's traditional districts, Lofoten and Vesterålen. Administratively it's located in the municipality of vågan, which is a municipality in Lofoten With its narrow entrance and steep-sided mountains, Trollfjord cuts westwards from the Raftsundet strait. To the East of the fjord lies Austvågøya. The name is derived from troll, a figure from Norse mythology.