This bunker is the forerunner of the nearby Biberbunker. It is a type 424 'küver', or 'Kustenverteidigung' (coastal defence) bunker with a brickwork day room and concrete night quarters. Radar data was gathered and processed in this building, which is why a 'Seeburgtisch' was installed here.
All relevant data concerning allied bombers was projected on a glass plate on the Seeburgtisch, but also that of the Germans' own fighter planes. The combat leader was therefore able to direct their own fighter planes towards allied bombers for interception operations. All relevant data, such as positions, altitudes and locations, came in via the powerful radar systems and was displayed on the Seeburgtisch.
As the air war progressed, the position of the German occupier weakened and the threat of bombing and invasion increased. This motivated the build of a larger and safer bunker in 1942: the Biberbunker.
This bunker can be visited on a guided tour. Make sure to bring your torch along so you can see the building properly.