The caverns remained unknown of for many years until the Third Era, when the Hero uncovered the hidden location during the Oblivion Crisis, with the help of Mages Guild scholars and operatives of the Blades.
The Hero traveled there to recover the Mysterium Xarxes, and after successfully infiltrating the Caverns, witnessed the leader of the Mythic Dawn, Mankar Camoran, leave Nirn for his Paradise. The Hero succeeded in recovering The Mysterium Xarxes, and in doing so, destroyed the shrine and the Mythic Dawn stronghold. The Mythic Dawn abandoned their base in the Cavern following this, and lost a major location in Cyrodiil.
- After the quest, Dagon Shrine is complete, Lake Arrius is still inhabited by Mythic Dawn Agents.
- After the Quest, the Shrine itself and Storeroom are shut off from access.
- This is a spawn point for very powerful, high-level enchanted gear and equipment, including Rings with 100% Fire resists, Disease resists, frost resists, and Shock resists.
- Mythic Dawn Agents are easy to kill under most circumstances so this spot is a very very good area to farm for special gear or valuables.