Here is link to their website:
Marine Kusten Batterie 1/512 Tromsö Süd was establishd short after the German occupation of the area in 1940. The batterie sorted under Artilleriegruppe IV/971 Balsfjord. It was armed with three 10,5 cm SKL/45 C/06 guns with a range of 14000 meter.
Below is a few pics and a video of the place, and I hope to get an appointment and another visit here very soon, and will then add more pics and info.