The update, which is free to all who own Rare's seafaring adventure, it's set to launch at the end of the month, and will add new features and a time-limited campaign.
The Brigantine, a new ship specifically designed for a crew of three, is being added alongside an Alliance system, allowing players to band together to tackle greater challenges and share the rewards.
Fans of the game's lore may be interested to know that things are afoot with the shopkeepers in Sea of Thieves and "a tale of ambition and greed escalating into something truly terrible will come to light in Cursed Sails." The first details of this story can be read online in the Pirate Times.
The time-limited campaign that introduces the new elements in Cursed Sails offers up some in-game rewards for those who are victorious. If you happen to miss out, fear not, as the Brigantine ship, the Alliance system and the crews of marauding skellies are permanent additions to the game.
If you're still undecided on Sea of Thieves, check out our review.
Cursed Sails releases 31 July.
Are you looking forward to teaming up with friends to take on the undead pirates? Let us know below or over in the forums.