The Loot - When a coffer or chest is successfully opened, a single item or chunk of  FFXI Gil is obtained from it. Items from chests and coffers are handled in much the same way as mob drops; a solo character obtains them immediately, while in a group the item is put into the item pool. In zones with regular items in the chest or coffer, any of the items is chosen at random as the treasure. In some zones the map key item can be obtained from the chest or coffer; these are usually obtained the first time a character opens that chest or coffer. The only item from a chest or coffer that is given higher priority than a map are items used in quests, which are always obtained first. These quest-related items are always given to a character who has the quest activated regardless of the character's current job, even if the quest required a different job to start it. This is possible even for Artifact quests; for example, the Old Gauntlets item can be obtained by any job once the appropriate quest is activated by the job that is getting the hands Artifact piece. A character who has a leveled Thief job can also pick a chest or coffer for any quest-based item as well, and obtain it without procuring the chest or coffer key. Note that this is only possible when obtaining an item used in an official quest (a quest shows up in the character's quest log.) There are Mini-Quests throughout the game that do not show up in the quest log, which can require that the character be a specific job when opening a chest or coffer to obtain an item.

The following is the order that a character obtains items from a Chest or Coffer, from highest priority to lowest. The first three selections can only be obtained once; a reward of FFXI Gil or a random item is always provided last, if none of the other options are available.
Quests: An item obtained from or used in a quest is always obtained first, whether Artifact or a regular quest.
Mini-Quests: Items obtained from or used in a mini-quests are next, primarily Artifact rewards that are only obtained when the character opening it is a certain job.
Maps: A map key item is obtained next, if there is one for that zone's in-game map.
FFXI Gil or Items: Either gil OR one of the items that can load in the chest/coffer is chosen, as listed below for each zone. These are the lowest priority, and are only obtained if none of the previously listed options are active. As more chests or coffers are found in the zone by a character, more gil or items chosen randomly from the pool are awarded.
The gil that is obtained from a chest or coffer can vary; there is a range of gil that can be obtained when a chest or coffer is opened. For example, the Crawlers' Nest Chest can load from 5500-8500 gil in it. If a character opens it alone, they will receive a randomly chosen amount of FFXI Gil within that range; when it is opened in a group, each character in the group obtains a slightly lower amount of gil, but the total FFXI Gil rewarded is far more than any one character could get by themselves.

Chest and Coffer List - All of the chests and coffers available are listed below, arranged by the zone that they are in. The known range of FFXI Gil that can be obtained is listed, along with the items that can load in the chest or coffer.