https://wccftech.com/sea-of-thieves-closed-beta-january-24-29/

Today Rare shared the official details for the upcoming Sea of Thieves Closed Beta. The event will run from January 24th to January 29th and be available for those who pre-purchase Sea of Thieves or registered for the Insider Programmer before December 1st, 2017.

Sea of Thieves will be out on March 20th, 2018 for Windows 10 PC and Xbox One. It’s an Xbox Play Anywhere title, so you can purchase it once and play it on both platforms with cross-save functionality, and there’s also cross-play should your friends be playing on the other platform.