I believe that it is possible that mermaids exists , as I agree with what Brian has said , they are probably from the realm of the Nagas . This could also be the reason why they have been sighted by certain people only and not all . I have heard that nagas are describe to be half human and half serpentine , mainly dwelling in the watery realm . So could this so called sightings by non buddhist practitioners be actually chance sightings of nagas ? Another consistent account is that these so called mermaids are never describe as the sweet and adorable mermaid in the " Little Mermaid " movies but always given a fierce and almost monstrous appearance .