It symbolizes knowledge, inner richness that only a dangerous quest can achieve. If we do not reach the treasure as we wished, then it indicates desire for perfection and despair for not having reached yet. If we find the treasure full of dirt and corroded by time and humidity, then it is a way to recognize internally that the desired treasure was exclusively material and perishable. If what we find are worthless objects, then dream indicates that our desires to be rich are utopians.
Read more about dreaming of Treasure in other dream meanings interpretations.