In this first incarnation as a mammal, the Lord fulfills another task. He engages in a battle with Hiranyaksha, a being with demonic qualities, who tries to block his path while he lifts earth out of the water. Following a long fight (divine play), this asura, who wants to seize earth for evil beings, is annihilated.
This manifestation of the Lord may symbolize the development of understanding that reaches beneath the shallow layers of available (and visible) information. Just like Varaha dives into the ocean for earth, we are expected to plunge deeply into our area of study or yoga, if one is a spiritual seeker, to come up with an actual and usable result for the world. Such search for knowledge almost always takes place behind the scenes (under water); only the results later become visible to fellow beings. To resonate this notion, Vedic Astrology** associates this incarnation with the planet Rahu, which signifies research, deeper intellectual abilities, and hidden powers.
*Source: Srimad Bhagavat Purana
** In a previous post on astrology, we have already seen that Rishi Parashara classifies Varaha as an incarnation devoid of jiva-tattva.