The biggest town in Nedre Eiker is Mjøndalen. The municipality is divided by the Drammenselva river.
Nedre Eiker is the primary orchid growing municipality, twenty-four of thirty-four registered orchid species are found here.
The poet Herman Wildenvey was born 20th July 1885 at Portåsen in Mjøndalen. He married to Gisken and the couple settled (Hegrisheim) in the coastal town of Stavern in 1923 and this was their home for the rest of their lives.