Source: Bestiary, pg(s). 243
A sea hag is a type of hag. They are usually solitary, but sometimes gather together in covens of three hags (of any type).
They delight in discord, and torment sailors and those who live by the sea.
In its natural form, a sea hag appears as an emaciated crone draped in seaweed.
A typical specimen is between five and six feet in height, and 160 pounds in weight. 
Sea hags lack the magical abilities of other hags. However, their appearance is so horrific that the sight of them can weaken any non-hags forced to look upon them.
They also have the ability to affect others with the evil eye. This curse can send victims into a coma, or even kill them.
If forced into melee combat, they rely on their sharp claws.