Devil Fruit

You have eaten one of the elusive devil fruits. These fruits offer great power in exchange for a weakness to water. The type of fruit determines the kind of power you get. There are Logia, Paramecia, and Zoan type fruits. Logia will allow you to transform and have control over some kind of element, like fire or ice. Paramecia grant strange and varied abilities, from turning into rubber or being able to split your body into multiple pieces. Zoan type fruits give you the ability to transform into animals, or into a beastly hybrid of animal and human. 

Regardless of what kind of power you have, you gain the following detriments:

• If you are in any liquid up to your ankles, you can no longer activate your devil fruit abilities
• If you are in any liquid up to your shins, you have disadvantage on ability checks and attack rolls. 
• If you are up to your waist in a liquid, you move at half speed. 
• If you are up to your neck in liquid, you must take an action on each of your turns to keep your head above the water. You cannot take bonus actions. Your speed becomes 0.
• If your head is below the surface of the water, you are paralyzed.

The exact parts of your body that are underwater don't matter, just the overall amount that is below the surface.