https://www.gamespot.com/articles/sea-of-thieves-promises-six-free-content-updates-t/1100-6458240/

Rare has issued a roadmap detailing its upcoming plans for Sea of Thieves on Xbox One and PC. The centerpiece of the plan includes big content updates through the rest of the year. Those big updates will be supplemented by regular weekly events with new goals and rewards. The weekly updates and regular content updates will be available for free.

The first big update, coming this May, is called The Hungering Deep. It will add a new AI threat, as well as new mechanics and rewards. This summer, the Cursed Sails update will include a new ship type, and then Forsaken Shores will add a new area to the map. After that, three more updates are planned for release by the end of 2018.