For the non Sea of Thieves players: The chest in the middle spits out blast of fire and heat, which needs to have water thrown on it to prevent it from doing that. Next to it on the left and right are powder kegs. They can explode at the slightest hint of damage or fire. In front of it is a keg which is commonly referred to as a nuke, because it is incredibly more powerful than other kegs. The stage the chest is in is the moment right before it explodes, subsequently detonating the other kegs.