Chests contain a verity of bits, food, and equipment. Chests can be opened by pressing up while the player is standing before a chest. There are several types of chests, their color indicates what they contain. Luck greatly influences a chests contents. It'll help prevent you finding duplicate items, making it easier to obtain items you do not yet have. Luck also grants better odds of finding larger amounts of Bits and high quality foods.
Co-op
In two player co-op mode, opening a chest grants an item to each player, but the player that opened the chest has a higher chance of obtaining rarer items.
Brown Chests 
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These are the most common of the chests. Their contents are randomized and will once again be loot-able if the player dies or returns to the world map. You'll find only Bits and food inside of these ones. They're however the only chest that can contain food, making them invaluable to a player in need of healing.
This chest can be thought of as two different chests despite them looking exactly alike. The first will only distribute bits and the other, a random food item. The placement of these chests never change so if you remember which ones contain food, you can save it for later, or, ignore it entirely if you don't require healing.
Red Chests 
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Red chests contain a large variety of equipment. Like the brown chests, their contents are randomized and will once again be loot-able if the player dies or returns to the world map. Inside you'll find Weapons, armor, accessories and unique to this chest, skills. These chests are here to fill in your arsenal for the challenges that lie ahead.
You'll find two of these chests per stage for the six main stages. One before and after the mid boss halfway-point. The two chests in the same stage also have their own separate loot pools.
Gold Chests 
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Rare and often hidden away, these chests contain a predetermined unique item. Once one of these chests have been looted, they'll remain empty for the rest of the adventure.
Blue Chests 
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You'll find weapons, armor, accessories and Bits inside these chests. However these chests are buried underground, you'll require a Dowsing Stick or PDA to locate them. The aforementioned accessories will create a pulsing sound when one is nearby. When the pulse becomes rapid, crouch at the location to reveal the blue chest.
For the main six stages, there will be exactly one of this chest hidden at a possible blue chest spawn location per visit. As for Canterlot, there is guaranteed to be a minimum of four blue chests spread throughout the areas of the castle. Their locations in the castle will be re-randomized whenever you leave Canterlot, die or visit a save point.
White Chests []
Only two of this chest exist, both of which are located inside Skeleton Cave. Each time you manage to surpass the caves trials, you'll be able to loot one of these chests. The two white chests contain a random weapon, accessory or skill from their respective loot pools.
Green Chests []
Green chests always contain Water of Life. They respawn within a stage if you are defeated there, but once you have beaten the stage's boss they will never be found there again. A green chest will be found in the Everfree Forest, in Cloudsdale, in the Appaloosan Mines, and in an unexpectedly magnanimous gesture - the second half of the Realm of Chaos.
Purple Chest []
This rather peculiar chest is found in only one location: an otherwise empty chamber in Castle Canterlot. Opening this chest summons the Siren Gem and seals off your exits, leaving you with no choice but to battle this glittering foe.