The pirate captain with his chest
The Arena Treasure Chest appears every 3 hours (starting at midnight, server time) in the middle of Gurubashi Arena in Cape of Stranglethorn as part of the Gurubashi Arena Booty Run event.
This chest contains some money, [Arena Master], a few greens, and other miscellaneous items.
It may also have a chance to contain the following:
Once a player has completed [Gurubashi Arena Grand Master], they can loot the [Defending Champion] from the chest.
The chest also has a chance to drop [Gladiator's Healing Potion].