Sea of Thieves is a pretty expansive and largely open game that leaves the adventuring up to the players themselves. The tasks you choose to take on and factions you choose to work with are up to you as a captain of your own ship. The chest of rage in Sea of Thieves is one of the treasure hordes that can be hunted down as part of the voyages in-game.
The chest of rage in Sea of Thieves is one of many different chests in the game. There are quite a few of these items in the open-world game, each one with their own unique missions, locations, and a few different requirements. These chests can be turned in with a variety of different factions to gain reputation and a ton of cosmetic rewards for both your ships and avatars.
To find the chest of rage in Sea of Thieves, you need to head to a very specific point on the map. Head to map coordinates between W16 and W17 and look for the Skeleton Fort in Molten Sands Fortress. This particular Skeleton Fortress only spawns every so often, and it is a one-off world event until it respawns. The mission itself is a pretty tough combat effort, with 15 total Skeleton waves that include three waves of Captain units. But if you head to those map locales and it has not spawned, there is another option.
The Chest of Rage is a special reward for three specific Crews of Rage mercenary voyages. These group-based missions are a unique endgame activity that can be undertaken by speaking to Duke at any in-game bar. Players should look out for the Bounty of Raging Shores, Bounty of Raging Wilds, and Bounty of Raging Ancients mercenary missions to get a shot at the new unique chest.
The chest of rage in Sea of Thieves is a unique chest that like other chests can be turned in for gold or used as a special little prank. Whereas the Sorrow constantly issues water, flooding enemy ships, the Rage chest can easily explode, instantly destroying the ship it is on.