Broken Swamp

Several rich castles and manor houses stand flooded in the Broken Swamp, a stinking hole west of the Hammerbound Peaks, with only spires and battlements showing above the dark waters. Sunken riches and powerful magic await those mighty enough to wrest them from their evil guardians.
 
The swamp has grown in recent memory, swallowing several farms and holdings along the mountains and lake, and it's now avoided by all but crazed adventurers equipped with water-breathing magic and looking for loot.