There is a fountain on the Greek island of Poros which contains this mermaid sculpture.
Mermaids have a long history in Greece, going back to the Sirens and the Nereids in Greek Mythology. The Nereids were sea nymphs or mermaids, and were daughters of Nereus, oldest son of Pontus (The Sea) and Gaia (The Earth), and grandfather of the hero Achilles.
This particular mermaid was created in 2004 by sculptor Giorgos Xenoulis of Athens, and placed in the fountain on the harbor waterfront of the small beautiful Greek island of Poros, about 30 miles southwest of Athens.
The island is very hilly and mountainous, with rich vegetation, and is a popular tourist destination with a rich history going back thousands of years.
The Poros Mermaid has become a symbol of the town and the island. While I have not found any evidence of a local mermaid legend, there likely is one, just as there is for the other mermaid sculpture by Giorgos Xenoulis on the island of Syros.
There is a page with more details and photos for the Mermaid of Poros.