Once a mighty pirate ship, Deathwail was captained by the dreaded pirate known as simply as Redeye. A man prone to unspeakable acts of Violence, Redeye and his ship Deathwail were finally destroyed in a horrible battle. However, Redeye was not to be counted out. Prior to the battle, he had plundered an ancient tomb, and had found a relic which he had kept. This item was cursed, and when he and his crew died, it brought them back in a horrible mockery of life. Enslaved by this relic, the pirates scour the waters, looking for souls that can be fed to the evil relic
Real World: some Indians in the Amazon treat their eyes with a traditional potion applied with palm leaves. Brutally painful, the drug alters vision, giving the jungle's dense green walls greater texture and dimension. You could adapt this to desert or swamps, or other hard to navigate regions.