A postcard on Blue Grotto (Taht il-Hnejja) in south coast of Malta. It is actually a number of sea caverns near Żurrieq where it becomes famous tourist destination. It could be reached by sea. Thanks Baldacchino.
A €0,63 stamp on French period of Malta was used but it was not postmarked. However, orange-color bar code at the bottom left of this card indicated it went through postal delivery system.