Aside from normal, blue water, there is also black water.
Black water is corrupted water that transforms everything it comes into contact with. What the black water acquires, it transforms into a bony version of the original. The black water can consume living beings, as well as inanimate objects such as ships, islands and stones. It can also transform other living things, such as plants or trees. The resulting version after the transformation is driven only by two desires: to feed the black water and to consume living flesh.

The black water calls to all its prey.
The longer its victims stay away from the black water, the stronger the urge to return to the black waters once more becomes. If a victim stays away from the black water for too long, the victim suffers from withdrawal syndrome, whose symptoms are increased desire to return to the black water, increased desire to consume living flesh and increased desire to return additional victims to the black water. In addition, the longer the victim stays from the black water, the more the newfound instincts begin to manifest and take over. This means that the victims’ cunning and aggressiveness will increase to achieve its/his/her goals.

The longer a victim stays transformed due to the black water, the more powers, cunning and aggressiveness the victim begins to develop, similar to the withdrawal syndrome which enhances these traits. In later stages of the transformation, the victim begins to acquire new powers such as being able to transform itself/himself/herself to fool his/her/its victims. These powers grow stronger the closer the victim is to black water.

Many of the powers require proximity to black water and some require that the victim submerges or is submerged in black water to work.

The curse of the black water is a strong one. Its effects take its toll on its victim. If the victim is not strong enough, it/he/she will disintegrate over time as the effects evolve. If the victim can withstand the transformation, he/she/it will become a formidable enemy to any and all prey the black water desires.

In advanced stages of the transformation, some may even be able to keep physical form other than their bony outline which the black water curses its victims with as they come in contact with it.

As prey approaches the black water, it will extend hands to try to grab whatever it can. These hands are made of the black water itself and thus cannot be harmed. However, they do not possess the abilities of the water itself and does not induce any effects. For the effects and transformation to take place, the victim must become submerged into the black water.
The transformation takes place as a victim touches the black water. Anything that is submerged will be transformed. That implies that even if a victim is half submerged, half of the body of such a victim will be transformed and imbued with the effects of black water. Eventually, this will spread to the rest of the body, however.

Some may be able to resist the corrosive power of the black water and retain their physical form even after being submerged. However, even so, the effects of the black water will still be applied. The curse will eventually try to corrode such a being from the inside. Even if the black water fails to corrode the victim, the victim will still be subjugated to the effects of the black water.

The water itself is corrosive and will corrode anything it touches. Being submerged in black water is extremely painful as the skin, muscles, organs and everything else will corrode away.
The black water, however, is not a sentient being, but a mindless entity which runs on instincts. It does not think; it does not wish; it does not desire. It merely does what its instincts tell it to do.

The black water is completely magic resistant and cannot be harmed by any mortal magic. Further, it creates a devious field in the air where it resides. This field hinders magic (any magic cast tends to go wrong in some ways) and causes unpleasant effects to anyone who traverses it. These symptoms include nausea, difficult of concentration, irritated skin and eyes, sea sickness and more. Anything transformed by the black water is unaffected by these symptoms.
To further this, this field also affects whether in the region. It causes rain to be corrosive, lightning to strike more frequently and with more accuracy, and snow turned into cubes of ice, among other conditions. The black water is also highly conductive, which means any lightning strike carries a charge through the water for a huge area.
The climate at the black water is also warmer than normal climate. The black water is also foggy. The deeper into black water territory that is traveled, the deeper the fog becomes. The air is sticky and slightly corrosive. Enough to cause skin irritation, but not enough to actually corrode things it touches, such as skin, clothing, or any other material. However, it does cause corrosion over time which causes metal to rust quicker than usual.

The effects of the black water cannot be reversed, nor slowed down (although with the exceptions of deities). The creator of the black water is… Eretria.