Beachgoers rushed out of the water after spotting a fin ominously emerging above the waves at a Spanish beach.

Locals and tourists were seen running up and down the sand to alert swimmers as they feared a shark was about to launch an attack.

The mystery sea creature stalked the shore of the beach in La Antilla, a small resort town in the municipality of Lepe in southwest Spain.

Panicked sun worshippers were seen looking on in horror in dramatic footage as the animal approached on Tuesday.

Its fearsome fin hovered above the shallow waters while it splashed around just metres away from swimmers and youngsters on paddle boards.

The creature loitered for just over a minute as a crowd of people gathered on the beach before it headed back out to sea.

But its explosive appearance inevitably caused a stir among locals who were desperate to find out what it was.

Most people assumed it was a shark due to the huge spike in sightings off the Spanish coast throughout the year.

Local police described the surprise guest on the shoreline as a Cuvier's beaked whale, the world’s deepest-diving mammal.

They encouraged residents to "stay calm" and put the shark rumours to bed in a social media post last night.