Black Salt Water Machine

In a world submerged by oceans infested with creatures each more dangerous than the last, pirates have become indispensable carriers for the inhabitants of the islands that populate the waters. In this world, pirates use the powers of tattoos given to them by a mysterious figure known as "The Witch". These tattoos give supernatural powers, but some pirates lose control of this power, making them very dangerous. Who is this Witch? Why do pirates lose control? Why not read this comic and find out?