Fluvenilstra was an Underdark city located 11 miles (18 km.) beneath the Shaar Desolation in southern Faerûn. The city was known primarily for its fungus forest and as a training ground for genasi who wished to mix their earth and water natures.
Some of the water that flowed through the Shaar prior to the Spellplague was redirected to Fluvenilstra and the city was well watered. The city was lit by luminescent fungi and many of the buildings were constructed from magically altered fungi.
Fluvenilstra had an armed force of several hundred.