It is amazing how the process of shaping the surface has resulted in similarities at different locations. Look at Tröllaskagi compared with the peninsula of Vestfirðir. Noticing that Ísafjarðardjúp has the alignment of equatorial mantle convection cells while Eyjafjörður has the direction of polar cells, the difference is about 22° of rotation for a match. In addition, the east coast of Skagafjörður and Arnarfjörður also match together. To trace the history of those two areas is a job for Superman.
Actually, the fit itself is not the mane issue here. The main issue is that this resemblance could be systematically searched for, because the rotation points are exactly 3° apart, representing the distance between the division lines of two convection rolls along the parallel of 66°N. At those two locations, similar conditions of mantle convection cells should prevail.