Blankenburger See, known locally as Blanki, is a quarry lake in Oldenburg used for diving, swimming, and fishing. It is an easy shore entry with a parking-trail access path, so the site works well for local training dives and relaxed practice sessions. The draw is a simple lake profile with reed-lined banks, submerged branches, and freshwater fish rather than scenic relief. Limited visibility makes it best for short, practical dives instead of long scenic runs.