Thalassar, The Sunken City

Location

Thalassar sits beneath a massive frozen lake at the northern border of the Kafu'im range, just north of Devindra's Desolation. The lake has no confirmed name in any current record — it predates the naming conventions of every civilization that came after. It is perfectly flat. Perfectly silent. Perfectly opaque.

The region is bordered on all sides by deterrents:

• South: Devindra's Desolation — the irradiated ruins of the Gnomish Empire, haunted by its own brand of hostile remnants
• North and West: The Kafu'im — a frozen mountain range that does not welcome passage
• East: Contested territory with no infrastructure and no reason to be there

This is not an area that sees traffic. The few who know Thalassar exists treat that knowledge as an asset, not a conversation topic.

What Is Known

Almost nothing, and that is the point.

• It was a civilization. Advanced. Underwater, or built somewhere that became underwater.
• It was obliterated or submerged at a point in history that does not appear cleanly in any surviving timeline.
• The lake above it is not natural. Or if it was natural once, something changed it.
• Mutated sea creatures have been reported by the handful of salvage divers who have broken through the ice and returned. The creatures are described as wrong — wrong proportions, wrong behaviors, wrong responses to light and sound.
• Lost technologies have been recovered in small quantities. None of them have been successfully reverse-engineered. Several have been confiscated by parties who have not disclosed what they found.

What Is Unknown

Everything else.

Who built it. What destroyed it. Whether anything down there is still running. Whether the wrongness of the creatures is a product of the environment or a product of whatever ended the civilization. Whether the lake froze to preserve what's beneath or to keep it contained.