Barrel is an environmental object found in Dragon's Dogma.
No Arisen is very far from a barrel in Gransys. These ubiquitous objects are easily broken open though they will often be empty rather than containing any loot.
Barrels can also be carried and stood on and this may have surprising benefits (see Badge of Vows 77). It is not possible, however, to obtain enough barrels to reach the ledge leading to Witchwood located just outside of Cassardis (see Witchwood notes section).
Barrels can be stacked. Generally the procedure is to place three barrels adjacent to each other, then jump onto one of the barrels. When standing on a barrel pick up a (third) nearby barrel below so that it is carried, then the carried barrel can be placed on the (second) barrel. This procedure can be repeated. Nearby environmental objects may help e.g. other crates, rocks, tables etc.
The practical limit to barrel stacking appears to be four barrels high, at this level attempting to stack more barrels usually causes the barrel stack to collapse in some way.
Barrel stacking offers a solution to many of the "Badge of Vows" quests in the From A Different Sky quest set, and may be especially useful to Arisen's lacking Levitate or Double Vault skills. For example, it is relatively easy to stack barrels directly below the platform where the Badge of Vows 25 is located in the Shadow Fort. Other usually inaccessible places can be reached, but certain locations are never accessible such as the bell towers of the village Chapel in Cassardis and of Gran Soren Cathedral.
Barrel stacking is only worth attempting in the absence of pawns, as they will almost certainly smash the barrels as soon as no other outlets for their weapons are available, sometimes before!
Stacking of barrels provides an alternative way to reach difficult locations, without skill such as Levitate, Stepping Stone, or Double Vault but is not necessary for the completion of any story quest. In some locations in Gransys barrel stacking attempts are stymied by barrels mysteriously disappearing if carried too far.