This is the brig. It’s the jail in a naval vessel, used to hold prisoners like enemy combatants or disobedient sailors. In Microsoft’s Sea of Thieves, it’s an option that a ship’s crew can use to isolate troublemakers. It can also be used to troll players. If the ship votes to put you in the brig, you’ll pop behind bars and you’ll be stuck there until the crew decides to let you out or you log out and try a different group.
On a real ship, you’d appear before the captain and he’d snarl for his bosun to toss you in the brig. In Sea of Thieves, you just appear in the cell. Unlike just about every other activity in Sea of Thieves, there are no instructions on how to be a prisoner. There is no minigame. You are just trapped.
That’s how I wound up spending an hour in the brig during this past weekend’s beta. I fumbled around thinking there was some puzzle or activity I had to complete to break out, but that wasn’t the case at all. My sin was being a random swabbie instead of one of the cool kids.