The sighting was made on Tuesday by local Luís Monteiro, during a daily morning walk.
Commenting on his Facebook page he said: “I had special company on my walk this morning.”
The shark is believed to be a Blue Shark, a non-aggressive species that feeds primarily on small fish and squid.
It is found worldwide in deep temperate and tropical waters, from the surface to about 350 metres.
According to factual data, in temperate seas it may approach shore.
Records from the Atlantic show a regular clockwise migration within the prevailing currents.