A large lake that is one of the few tributaries not running through the Feitas, Ceras Lake is a deep, artificial lake that was created in order to cover up the Ceras Lake Castle by the Sindar. The entire castle was submerged into the water, making it completely undetectable from the surface. If needed, however, the water could be drained or flooded by activating the ruins found in a cave next to Ceras Lake. These Sindar ruins effectively dam the water of Ceras Lake, and are controlled by a sluice gate mechanism inside the ruins.
However, access to this sluice gate is prevented if one does not have either the Sun Rune, Dawn Rune, or Twilight Rune; because of this, no one had been able to access the sluicegate until SY 449, when Prince Freyjadour Falenas activated it with the Dawn Rune, opening the sluice gate and revealing Ceras Lake Castle, as well as flooding nearby Hatred Fortress.
The Loyalist Army took over the pristine castle ruins for a time, declaring it their headquarters during the war. When it ended, however, they closed the sluice gate again, returning Ceras Lake castle to it's watery abyss once more.