I'm a new player, and ever since first I started playing through the Dead City area the game keeps adding the Stormy Seas quest at random points and across all my characters (even before I'd started playing Dead City with some of them).

It doesn't even happen just at random points either. Currently, if I delete the quest and go into an Ursoth's Assault boss battle, it will add itself when the first weed is killed in the first section of that map, like clockwork.