As this page suggests there are 3 bunkers on the Rijkswerf. 2 are plotted out but this 3rd one isn't on the map.
https://www.bunkerinfo.nl/2016/08/schuilbunker-1-rijkswerf-den-helder.html

Hi, this part of the road, connecting the parking place and the road, isn't there anymore. The parking is only accessible (car) from the Emmalaan.

Footpaths on this whole park are a bit off comparing to current footpaths. Please compare with aerial view.