Chests in general are used to hold treasure and keep it safe from thieves and the like. This means that beside locking mechanisms, they are often fitted with traps. The contents can vary significantly, determined by many factors (including which Ultima installment one is playing).
 By Game
 Ultima I
Chests can be found in only in dungeons, both at random and after defeating an enemy. They typically contain various types and amounts of coins.
The Unlock spell could be used to safely disarm and open a chest.
 Ultima II
Chests can be found either in dungeons or towers, both at random and after defeating an enemy. Various armour and weaponry can be found in some structures throughout the lands, but stored outside the confines of treasure chests.
 Ultima III
Chests can be found in dungeons and towns and are dropped when a group of enemies are defeated. They can be trapped and contain gold and sometimes an item.
- Traps: Poison, Gas Bomb, Acid, Bomb
- Gold: 12-27,48-63
- Other items: Mace, Leather Armor, Axe, Cloth Armour, Sling, Dagger...?
Drop research is ongoing and can be found here.
There is a rare monster that is a chest. In some versions (including the PC port) you can stand on top of it and open it, but you still enter combat.
 Ultima IV
Chests function much as in Ultima III, but do not drop items.
- Traps: Poison, Acid, Sleep, Bomb
- Gold: ?
The Open spell could be used to safely disarm and open a chest, as well as a high Dexterity.
 Ultima V
In the time of the Shadowlords, chests found throughout the realm could be locked as well as trapped, but could contain virtually any type of item that could be carried (aside from special quest items).
The An Sanct spell could be used to safely disarm and open a chest (as well as unlock many locked doors), as could a high Dexterity.
 Later Installments
(to be added)
Chests are not always harmless. Apart from the threat of mimics, normal treasure chests are often trapped by their owners in order to prevent any tampering with them due to potentially lethal consequences. However, the adventurer isn't completely helpless against these traps. With the detect trap spell, it is possible to find these hidden dangers. The unlock spell further opens these chests, while at the same time destroying the traps.
There are four different traps found in chests:
Seen only in Ultima III, this variant of the poison trap envelops the entire party in a noxious cloud, poisoning everyone in the group.
This trap is more nasty than the poison trap. Instead of poison, the thief is sprayed with acid. The acid is very damaging, and if not properly treated with the heal spell, has potential lasting health-effects.
This is the worst of all traps. Trying to open the chest will trigger a bomb-trap which will blow apart the chest, destroying its contents. The powerful explosion will seriously injure anyone nearby, meaning the entire party.