Karsoluthiyl

Karsoluthiyl was a drow city located beneath the Trackless Sea, west of the mouth of the River Chionthar.

Within the city the Jaezred Chaulssin established a hidden fosterage. During the War of the Spider Queen the members of the brotherhood weakened the hold of the ruling Matron Mothers and helped the male-dominated merchant houses gain influence.

Two prominant houses were House Tanor'Thal and House Lysaen. Both houses were big players in the slave trade of Skullport. Tanor'Thal had an outpost on the 5th level of Undermountain called Kyorlamshin, while Lysaen expanded into the 3rd level.

Geography
Karsoluthiyl is located in a region of the Underdark known as the Swordsea Depths, which lies underneath the Sword Coast. They are engaged in a struggle for supremacy with Aboleths, Svirfneblin, and Thaalud who also call the area home.

It is connected by long and arduous tunnel routes to Undermountain to the north, Sshamath to the east, and the realms of Deep Shanatar to the south. In addition it is at the end of a series of portals which link from Karsoluthiyl to sea caves in Ruathym, from there to caverns in the Crags near Neverwinter, to the Ubdermountain, another set of caves in Ruathym, and back to Karsoluthiyl.