- Björnholmen means a bear island. The island could be renamed for example the fortification island. A huge amount of bunkers, tunnels and gun positions has been constructed to the island. Not all has been completed, but even the unfinished structures alone are massive. The island has been in practice mined hollow. The sea fortress of Björnholmen has been located in the middle of the channel, which leads to Tammisaari. Because of this the island has been strategically important and that really shows in the amount and size of the fortifications.

- During the existence of Hanko Front, the Russians bombarded the island with artillery. This however didn't cause any real losses. A Russian submarine was also searched from the nearby waters, which however was not found. If there has been a submarine, it has been either laying mines or trying to get into position in front of Tammisaari.

- Either way, the island is definitely worth of visiting, even though the summer cottages have now occupied nearly every inch of the shoreline. The easiest place to get into the shore is the area near of structure 228. The shore however is full of sharp stones, which have come from the mined structure 228. The water is deep enough to approach even with a bit bigger boat. The structure 228 was never completed and only the unfinished tunnel is reminding about the structure.

- Because the shoreline is full of summer cottages, it is advisable to talk with the summer residents if possible. Otherwise the visit to the island will cause additional fuss and worry to the summer residents, who will recognize strangers walking around the place. One of the few structures, which is located right in the yard of a summer cottage is the structure 225. The structure is a bunker with two machine gun nests and with accommodation areas. The structure is the only one of its sort in Harparskog-line, which has not been locked. The interiors are quite big and differ from the bunkers, which can be found from the Harparskog-area.

- Nearby of the structure 225 is also the entrance of a tunnel into the structure 226, a, b & c. There is three entrances into the structure, from which one has been closed. Next to the two other entrances are the gun positions. One of the two gun positions is in good condition, but the other one has been buried under vegetation and under fallen trees. This structure however is the most interesting one in Björnholmen.

- Despite of the fact that the shores have been build up effectively, the structures are in a quite good condition and it seems, that the summer residents do look after of some of the structures. Only the dug and partly mined pit from the structure 311 seems to have disappeared completely from the area. The stones, which have come from the mining task, however can be found from the area, collected into a large stack.

- The island doesn't look too big in the map, but the reality is that you need to reserve the whole day to the trip, if you intend to visit every structure.

- My own personal notes below are based on the situation in the defensive line, during the years 2005 and 2006.