Oceania is the smallest region in Risk with 4 territories. The player that holds the regions gains an additional 2 reinforcements per turn.
With only one point of defense, Oceania is the easiest region to conquer and hold. Although in many games, a player's attempts at conquering it may be frustrated by opposing players who also want to quickly take the region. It is advisable to take the region if you begin the game with more territories in it than anyone, although it can still easily be taken with if you have one territory in it. If an opposing player also wants to take the region, be sure you place enough armies to defeat them so they will not be wasted. A problem with Oceania is that the player that holds it usually has a difficult time gaining enough strength to conquer other players. For a player who conquers Oceania, it is important to maintain territories outside the region if possible.