GNSS level monitoring of the Federal Institute for Water Science. It contains all relevant information for the evaluation of GNSS observations from all GNSS stations along the German Bay with a level reference. In addition to the BfG, this includes six GREF stations of the Federal Office for Cartography and Geodesy (BKG). In addition to information on GNSS systems, current altitude differences between GNSS markers and levels will also be provided. The BfG stations are firmly connected to the pearls (GNSS@tide gauge), while the six GREF stations are covered by cooperation between the WSV/BfG.