Bulgaria issued a sheet for the Danube European River of which one stamp and a label have a maritime connection.
The 25st stamps shows us a motorboat in front of the Baba Diva fort, see: https://en.wikipedia.org/wiki/Baba_Vida
On the craft I have not any info.
The label show us a hydrofoil passenger ship which I believe is stylized, I can’t find any exact details of this vessel.
Bulgaria 1978 25st and label sg?, scott?