There is a video available on YouTube showing the body of a mermaid stranded on the beach, titled "Echte Meerjungfrau nach Hurrican 2015 gefunden" (Real Mermaid Found After Hurricane 2015).
The upper part of the body appears human, while the lower part forms a large fin. It is suspected that such a body may have actually been found stranded, which could prove the existence of mermaids.
It turns out that this was just a hoax and an illusion, merely a property created by Joel Harlow for the film Pirates of the Caribbean: On Stranger Tides. To this day, there is no evidence of the existence of aquatic humanoids ever found.
In the past, Beluga whales were often mistaken for mermaids because they had "knees" similar to humans.
The photo that went viral was actually just a Beluga fish displaying its "knee," which should have been hidden under a thick layer of fat. What appeared to be a "knee" was actually an accumulation of extra fat surrounding a muscle that can be moved up and down; its function is to help the Beluga stay warm in its habitat in the very cold Arctic waters.
Under year-round cold sea conditions, any mammal other than whales or seals will eventually get too cold and die of hypothermia, whereas the Beluga whale manages to maintain the body temperature of warm mammals thanks to its fat reserves, which can reach about 40% of its body weight.
Just because the camera's viewing angle is correct, where the camera's position is such that it can capture the fat accumulation, it can actually be moved up and down.
In August 2009, after dozens of people reported seeing a mermaid leaping in the waters of the Mediterranean in Haifa Bay, a beach in northern Israel, the government of the Israeli coastal city of Kiryat Yam offered a reward of $1 million to anyone who could prove its existence, a prize that no one has yet managed to win.
Stories about mermaids appear in folklore cultures around the world, including Europe, Asia, and Africa. In the Javanese culture of Indonesia, Nyai Roro Kidul is the goddess of the sea and Queen of the Southern Sea, and has many forms; in her mermaid form she is called Nyai Blorong.