Encantado is Brazillian Portuguese for 'enchanted one.' The term is used for dolphin-like zoomorphic creatures that come from a paradisiacal underwater realm called the Encante.
They are said to transform into pale-skinned handsome men who dress in old-fashioned clothing. However, this is almost always a partial transformation, for the top of their heads are said to be hairless (presumably where the melon and blowhole is supposed to be situated).
Moreover, they are said to like music, women and parties. They are said to take the women to Encante where they are said to have illicit affairs with them, often resulting in illegitimate offspring.
Furthermore, it is said that they have weird special powers, such as controlling streams and bending humans to their will. It is often said that people transversing rivers and tributaries above their realm are said to go insane, just by their playful cetacean behaviour (nudging the boat or frolicking nearby).
Shamans and holy men are often needed to intervene and rectify the situation. To break the spell, a medicine man or wise woman must cast a magical powder -- a mixture of manioc flour and dried crushed chile peppers works well -- over the water where the Encantado is known to appear. This powder will usually break the spell and drive the creature away, and any gifts it may have given the victim, such as jewellery or fine clothes, will revert to their true forms: rotting leaves and other river trash. It is of critical importance to keep the victim away from the river, using restraints if necessary; they will be drawn to the water, pulled irresistibly by the power of the Encantado.
There are many similar tales pertaining to Dolphin Men emanating from Peru, Venezuela and other neighbouring countries.