Vanaheim is the original realm of the Vanir. This realm does not appear that much in the stories of Norse mythology, although it is mentioned that the Aesir tried to invade it once. Their invasion proved to be unsuccessful.
There is no description of what this world looks like, so we can only imagine. As it has been inhabited by the fertility gods, we imagine that it must be filled with many different lifeforms, including plants, trees, and animals. It must contain lots of water as well (equally rich with life), as Njörd used to be the ruler of Vanaheim before he came to live with the Aesir. It is said that he will return there after the events of Ragnarok.