Unterseen literally means "Lower Lake", which is correct, since Unterseen is located on the flat area on the eastern shore of Lake Thun between the two creek Lombach below the "Chienberg" to the north and the Aare to the south, which both flow into Lake Thun. The historic town however is mainly found at the northern bank of the Aare, which flows here from Lake Brienz to Lake Thun (therefore "lower lake"). Just across the Aare is the town of Interlaken. Both municipalities are located on the flat alluvial land among steep mountains, which is also called the Bödeli.