While in the Upper Halls of Tir Asleigh Keep during The Sunken Kingdom there is a small sidequest which does not appear in the journal. In the halls there are statues frequenting the niches, activating Nine statues corresponding to the divines will open a hidden room containing a cache of goodies and an altar.
The statues do not have activators; however when clicking on the correct one it will chime and shine with a heavenly aura. The hidden room which opens is in a room in the Upper Halls and near the entrance.
This quest can be done at any time after getting the key for the Upper Halls or after completing The Sunken Kingdom of The Oracle's Fire. If returning to Tir Asleigh to find the room, be forewarned the Water Dragons have not left the area.
The Nine Divines: Akatosh, Kynareth, Arkay, Dibella, Julianos, Stendarr, Zenithar, Talos, Mara