Ys

Ys is an underwater city in the sea off the coast of Bremervoord. Hidden by the tides, there is an actual staircase which descends to the city. Geralt discovers this staircase while investigating the deaths of some fishermen for Agloval, the local regent. It is there that the witcher encounters a race of intelligent sea creatures. Intelligent, yes! but friendly, not at all, so a battle quickly follows. It is only through the extremely timely intervention of Sh'eenaz that is Geralt able to escape. These events are described in the short story "Trochę poświęcenia" ("A bit of Dedication") in the Miecz przeznaczenia (The Sword of Destiny) collection by Andrzej Sapkowski.

In the game, Stones of Ys are used as alchemical ingredients. These are found in the remains of vodyanoi priests. It is likely that the vodyanoi in the game are meant to be the same creatures that Geralt encounters in the short story.